super absorbent containing web that can act as a filter, absorbent, reactive layer or fuel fuse

ABSTRACT

The web of the invention can comprise a super absorbent layer that can act as an moisture sensitive fuel shut-off valve, absorbent, adsorbant or reactant. The web of the invention can comprise a super absorbent fabric or layer made of a superabsorbent particle or fiber. The web can comprise a nanofiber layer having dispersed within the nanofiber layer a super absorbent particulate and optionally a second particulate material that can act as an absorbent, adsorbant or reactant. Fluid, gas or liquid, that flows through or by the assemblies of the invention can have any gas, liquid or solid material dispersed or dissolved in the fluid interact with the super absorbent particulate. If needed these materials can also react with, be absorbed by, or adsorbed onto, the active particulate within the nanofiber layer. The structures of the invention can act simply as flow-by reactive, absorptive, or adsorptive layers with no filtration properties, or the structures of the invention can be assembled into filters that can filter particulate from a mobile fluid in a flow-through mode while simultaneously reacting, absorbing, or adsorbing materials from the mobile fluid.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication 60/918,456, filed Mar. 15, 2007, which application is herebyincorporated by reference in its entirety.

FIELD OF THE INVENTION

The invention relates to a web or fiber structure with super absorbentproperties. The web, filter, element or medium structures of theinvention can also act as a reactive, adsorptive or absorptive layer orin a filtration mode. The structure comprises a fiber web and superabsorbent particulate, fiber, fabric or layer. The web can also comprisea reactive, adsorptive or absorptive particulate that also acts as anactive particulate, active material fiber, spacer or separation means.The webs of the invention can be used in a number of applications andmethods including absorptive, filtration or separation methods.

BACKGROUND OF THE INVENTION

Polymer webs can be made by extrusion, melt spinning, air laid and wetlaid processing, etc. The manufacturing technology of web structures isvast for obtaining structures that can separate an unwanted, entrainedparticulate load from a mobile fluid stream. Such materials includefilters and separation structures. Filter structures include surfaceloading media and depth media in which these media can be produced in avariety of geometric structures. Principles relating to the use of suchmedia are described in Kahlbaugh et al., U.S. Pat. Nos. 5,082,476;5,238,474; 5,364,456 and 5,672,399. In any filter structure containingany arbitrarily selected filtration medium, the filter must remove adefined particle size, and at the same time, have sufficient lifetime tobe economically justifiable in its particulate removing properties.Lifetime is generally considered to be the time between installation andthe time a filter obtains sufficient particulate load such that thepressure drop across the filter is greater than a predetermined level.An increased pressure drop can cause filter bypass, mechanical filterfailure, fluid starvation, or other operating problems. Filtrationefficiency is the characteristic of the filtration media that is relatedto the fraction of the particulate removed from the mobile stream.Efficiency is typically measured by a set test protocol defined below.

Surface loading filter media often comprise dense mats of fiber having anon-woven structure that is placed across the path of a mobile fluidstream. While the mobile fluid stream passes through the structure ofthe formed non-woven fibers, the particulate is typically removed fromthe stream at the filter surface with a certain efficiency and remainson the surface. In contrast to surface loading structures, depth mediatypically include a relatively (compared to surface loading media) thickstructure of fiber having a defined solidity, porosity, layer thicknessand efficiency. Depth media and in particular, gradient density depthmedia are shown in Kahlbaugh et al., U.S. Pat. Nos. 5,082,476; 5,238,474and 5,364,456. In general, depth media act in filtration operations byimpeding the particulate loading in a mobile fluid stream within thefilter layer. As the particulates impinge the depth media fibrousstructure, the particulate remains within the depth media and istypically distributed onto and held with internal fibers and throughoutthe filter volume. In contrast, surface loading media typicallyaccumulate particulate in a surface layer.

Groeger et al., U.S. Pat. No. 5,486,410, teach a fibrous structuretypically made from a bicomponent, core/shell fiber, containing aparticulate material. The particulate comprising an immobilizedfunctional material held in the fiber structure. The functional materialis designed to interact with and modify the fluid stream. Typicalmaterials include silica, zeolite, alumina, molecular sieves, etc. thatcan either react with, or absorb materials, in the fluid stream. Markellet al., U.S. Pat. No. 5,328,758, use a melt blown thermoplastic web anda sorbative material in the web for separation processing. Errede etal., U.S. Pat. No. 4,460,642, teach a composite sheet of PTFE that iswater swellable and contains hydrophilic absorptive particles. Thissheet is useful as a wound dressing, as a material for absorbing andremoving non-aqueous solvents, or as a separation chromatographicmaterial. Kolpin et al., U.S. Pat. No. 4,429,001, teach a sorbent sheetcomprising a melt blown fiber containing super absorbent polymerparticles. Deodorizing or air purifying filters are shown in, forexample, Mitsutoshi et al., JP 7265640 and Eiichiro et al., JP 10165731.

Many mobile fluid phases, including both gas and liquid phases, containundesirable components suspended, dissolved, or otherwise entrainedwithin the mobile phase. Such undesirable components may be chemicallyreactive or may be absorbable or adsorbable through the use ofabsorbents or adsorbents. Absorbents and Super absorbents arecharacterized by the degree of absorption. Often these species form aphase that is fully miscible in the fluid and cannot be filtered, butcan be removed only by chemical reaction absorbents or adsorbents.Examples of materials to be absorbed or separated include particulates,water in the form of dissolved water (humidity) or a dispersed waterphase (mist or spray). Other materials are acidic or basic reactingcompounds. Acid compounds include hydrogen sulfide, sulfur dioxide andother such species basic components include ammonia, amines, quaternarycompounds and others. Further reactive gases such as Cl₂, SO₂, cyanide,phosgene and others can pose hazards. Lastly, a number of othercompounds are objectionable due to odor, color or other undesirableproperties. The removal of all such materials from a fluid phase, ifpossible, can be helpful in many end uses. The active layers of existingsystems suffer from problems relating to the mechanical instability ofthe particulate in the layers. In many structures the particulate is notmechanically fixed in the layer and can be dislodged easily. In manystructures, the amount of active materials available is limited by thenature of the substrate and the amounts of active material that can beloaded.

Donaldson Company has also filed U.S. Ser. Nos. 60/773,067, 11/354,301and PCT/US2007/004043. These applications disclose related nanofiberwebs containing particulate materials. These particulate are biologicalmaterials, inert particulate that act a spacer materials providingreduced solidity and other physical attributes and active adsorbant,absorbent or reactive particles. These structures provide reducedsolidity, reactive adsorptive and absorptive capacity and otherattributes.

Super absorbent, absorbent or water swellable anionic polymers are usedin certain consumer articles and in industrial applications. Theseapplications typically relate to disposable articles in consumer,hazmat, etc. applications. These typically comprise crosslinked acryliccopolymers of alkali metal salts of acrylic acid and acrylamide or otherhydrophilic monomers such as 2-acrylamido-2-methylpropanesulfonic acid.

While both surface loading media and depth media have been used in thepast and have obtained certain levels of performance, a substantial needremains in the industry for fluid phase separation, treatment andfiltration media that can provide new, different and enhancedperformance characteristics than have been formerly obtained

SUMMARY OF THE INVENTION

The web, filter, or other flow-through or flow-by structure of theinvention can comprise a layer comprising a superabsorbent particulate,fiber or fabric. The superabsorbent layer can be a part of asubstantially continuous nanofiber layer or can be used with such alayer . Optionally a reactive, absorptive, or adsorptive fiber spacer orseparation means in the form of a particle can be combined with, orotherwise dispersed in, the fiber mass containing the super absorbent.

In one aspect, the web comprises a continuous fibrous structure with asuper absorbent nonwoven that can treat a fluid stream, in a flowthrough or flow by mode. The fluid stream can be a gas, or liquid withentrained materials. The entrained materials can be soluble or insolublein the mobile fluids and can be particulates of either liquid or solidimpurities. Liquid water is a common impurity in fuel. The liquids canbe exemplified by aqueous solutions, nonaqueous fluids, water, oils, andmixtures thereof.

In another aspect, the web comprises a continuous fibrous structure witha continuous superabsorbent fiber phase or a super absorbent particulatephase. The fuel can be treated such that entrained or dissolved watercan be reduced well below water saturation concentration. In Jet A fuel,for example the saturation concentration is about 120 ppm on the totalfuel. Such a phase can be used to treat a fluid stream in a flow by modewith no filtration aspect. The fluid stream can be a gas, or liquid withentrained materials. The entrained materials can be soluble or insolublein the mobile fluids and can be particulates of either liquid or solidimpurities. The liquids can be exemplified by aqueous solutions,nonaqueous fluids, water, oils, and mixtures thereof.

In a second aspect a similar structure can also act as a filter in aflow through mode. The super absorbent fiber fabric or particulate isdispersed in or used with the nanofiber web. The filter can be used tofilter a mobile fluid such as a gaseous stream or a liquid stream. Thefilter can be used to remove impurities from the liquid stream or fromthe gaseous stream. Such impurities can be entrained particulates. Theflow through and flow by structures can be used in structures that needno PTFE, stretched expanded Teflon® or other related porousfluoropolymer components for successful activity.

One additional aspect of the invention is a method of preventing theintroduction of contaminated water fuel into a fuel reservoir using“shut-off”, valve or “fuse” properties of the super-absorbent nonwoven.In “shut off” or “fuse” mode, an element used in a flow through mode,containing the super-absorbent nonwoven absorbs water in the fuel andbegins immediately to swell sufficiently such that the swollen materialsfill the area and stop fuel flow. This mode is useful in aviation fuelapplications where water contamination is common and can cause enginefailure. The fabric compositions of the invention rapidly stop flowwithout contaminating the fuel with any contaminant particulate ormaterials from the fuse.

The compositions of the invention can comprise a nano fiber and a wovenor nonwoven superabsorbent layer or a combination of nanofiber andsuperabsorbent particulate or fiber. The superabsorbent fiber is in theform of the nonwoven layer. In such a structure, the nanofiber layer isformed in conjunction with the superabsorbent nonwoven layer. Suchnonwoven layers typically comprise a nonwoven structure made of superabsorbent fiber using typical nonwoven manufacturing techniques. Thenonwoven layer can comprise substantially all superabsorbent fibers orthe fibers can be combined with secondary fibers and other woven ornonwoven, film or sheet layers. Secondary fibers that can be used incombination with the superabsorbent fibers are discussed separately inthis disclosure.

The nonwoven comprising the superabsorbent fibers can be used with otherlayers such as film layers, microporous film layers, mesh layers, scrimlayers, filtration support or media layers or other layers useful inproviding structure or other useful properties to the nonwoven layer.The nonwoven layer can be substantially all superabsorbent fiber or canbe a combination of superabsorbent fiber and secondary fiber. When used,the proportions of superabsorbent fiber to secondary fiber can rangefrom about 95 wt % superabsorbent fiber and 5% secondary fiber toapproximately 5% superabsorbent fiber and 95% secondary fiber. Further,the nonwoven structure containing the superabsorbent fiber can haveseparate layers of nonwoven materials. Such structure can contain 1-3 ormore layers of nonwoven fabric typically 2-5 layers of nonwoven fabricwhere the multilayer structure is used. The layers can be substantiallysimilar or can be substantially different in both materials andconstruction. For example, one layer can comprise substantiallynon-superabsorbent nonwovens while a second layer can comprisesubstantially all superabsorbent nonwovens. A third layer can comprise acombination of superabsorbent fiber and secondary fibers. Variations andcombinations of different layers and different combinations ofsuperabsorbent fibers and secondary fibers are contemplated within thisdisclosure. Preferred superabsorbent media is an airlaid media made byConcert Industries: DT 325.100 airlaid grade manufactured with Type 101superabsorbent fibers made by Technical Absorbents. The superabsorbentfibers were 10 dtex fibers and were 6-mm long (typical airlaid sizes);they are a sodium polyacrylate polymer. The composition of the airlaidwas ˜40% superabsorbent fiber, 30-40% cellulose, and 20-30% polyesterbicomponent. The current properties of the media include a basis weightof 325 g/m², a thickness of 2.5 mm (0.1 inches), a density of 0.1 g/cm³,an absorbent capacity of 35 g water/g media and a dry tensile of 9.5lb/in.

In the nonwoven embodiment, the superabsorbent fiber can be formed intoa discrete layer, dispersed in other fiber layers or dispersed in thenanofiber. For the purpose of the particulate superabsorbent embodiment,by “dispersed in the web,” is meant that the particulate or superabsorbent particulate is adhered to the fiber, held within a void spacewithin the web or in a pocket penetrating partially into the webcreating a space in the web surface. Once formed, the web comprising thenanofiber layer containing the super absorbent particulate of theinvention can be combined with a media layer. That form can be used in aflow-by treatment unit or used in a flow-through filtration unit havingadsorptive/absorptive or reactive properties. In a flow-by orpass-through unit, the media is simply configured in a form throughwhich the mobile fluid can pass over the web unimpeded by any filtrationlayer and simply contact the absorptive/adsorptive or reactive speciesformed in the nanofiber layer adjacent to the flow path of the fluidmedia. Alternatively, the nanofiber layer containing the activeparticulate and media can be formed in a flow-through filtrationstructure that can remove particulate from the mobile fluid while in theinfiltration mode, the media of the invention can, in a filtration mode,remove the entrained particulate from mobile fluid and at the same timeabsorb, adsorb or chemically react with unwanted materials in the fluidphase that may or may not be in a particulate form.

The term filter refers to the structure that is actually used intreating a mobile fluid in a flow through mode. A “filter” usuallyincludes housing with an inlet and outlet. The term “element” typicallyrefers to a structure that can be easily placed and replaced in a filterstructure during routine maintenance.

The web of the material can also have a gradient structure. In thisdisclosure, the term “gradient” indicates that some component (density,solidity, fiber size, etc.) of the web varies from one surface of theweb to the opposite surface of the web. The gradient can becharacterized by a variation in amount of active particulate, varyingproportions of active and inert particulate, or other variation inparticulate. The gradient can also be characterized in terms of avariation in the weight or the number of fibers. The gradient is formedby forming successively more or less fibers or more or less particulateswithin the web as the web is formed. Further, the concentration ofspacer means or particulate can have a gradient aspect in which thesize, weight or number of particulate materials per volume issubstantially increased or reduced from one surface of the web to theother. The media of the invention can be used in the form of a singlenanofiber web or a series of fine fiber webs in a filter structure. Theterm “nanofiber” indicates a fiber having a fiber size or diameter of0.001 to less than 2 microns or about 0.001 to less than 1 microns and,in some instances, 0.001 to 0.5 micron diameter.

For the purpose of this patent application, the term “adsorptive”indicates a particle that is active to adsorb and accumulate materialfrom a fluid stream on the surface of a particle. The term “absorptive”indicates that the particle has the capacity to accumulate material froma fluid stream into the interior or void space or spaces within aparticle. “Chemically reactive” indicates that the particulate has thecapacity to react with and chemically change both the character of theparticle and the chemical character of the material in the fluid stream.A “fluid stream”, in this application, indicates either a gaseous or aliquid stream that can contain a dispersed or dissolve contaminant suchas a particulate or water component. The particulate can be eitherfiltered from the fluid stream or the particulate can be adsorbed,absorbed or reacted with the particulate material of the invention. Theterm “active particulate”, when used in this disclosure, refers to theabsorptive, adsorptive or reactive particulate. The term “inertparticulate” refers to a particulate that has no substantial absorptive,adsorptive or reactive capacity. Such particles can be used as aseparation means or to occupy space.

For the purpose of this invention, the term “media” includes a structurecomprising a web comprising a substantially continuous nanofiber mass.The media can comprise a support web and other components. Theseparation or spacer materials of the invention can be dispersed in thefiber or can be combined with the nanofiber layer. In this disclosurethe term “media” indicates the web of the invention, comprising thenanofiber and dispersed particulate in combination with a substrate ofsome active or inert type disclosed herein. The term “element” indicatesthe combination of the “media” of the invention with another componentincluding cartridge components in the form of (e.g.) cylinder or flatpanel structures. In this disclosure, the term “web” includes any fabricor film layer and can include the substantially continuous or contiguousnanofiber phase with or without the spacer or particulate phase. Acontinuous web is necessary to impose a barrier to the passage of aparticulate contaminant loading in a mobile phase. A single web, twowebs or multiple webs can be combined to make up the filter media of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the flow diagram of the test system, which was used tomeasure water concentration of test fuel before and after it wasfiltered through composite samples

FIG. 2 shows a cross section view of a composite with a super absorbentparticle trapped inside a nanofiber matrix

FIG. 3 shows the top and cross section views of a composite wherenanofibers are used to treat the surface of a super absorbent nonwovensubstrate

FIG. 4 shows the optical microscope images of copper sulfate stainedmembranes after effluent diesel has been filtered through them; residualblue stain is an indication of the presence of super absorbent particles

FIG. 5 show the cross section view of a composite comprising asubstantially continuous nanofiber mass containing super absorbentfibers

FIGS. 6 to 8 illustrate the fuse, valve or shut off and pressure dropcharacteristics of the constructions of the invention

DETAILED DISCUSSION OF THE INVENTION

The fabric, web, filter, or other flow-through or flow-by structure ofthe invention can comprise a substantially continuous nanofiber mass anda layer containing the super absorbent particulate, fiber or fabric ofthe invention. The fabric, fiber and particle or fiber can be made byfiber forming techniques and fabric weaving or nonwoven manufacturingprinciples. The fiber can be made by forming fiber from a SAP fiber or acombination of polymer and SAP or fiber. Alternatively the SAP or fibercan be added to the fiber after formation. Optionally a reactive,absorptive, or adsorptive fiber spacer or separation means in the formof a particle can be combined with, or otherwise dispersed in, the fibermass containing the super absorbent. The particulate in a web mustcontain at least some super absorbent particulate but can also comprisean amount of another particulate or blend of dissimilar particulates.For example, a superabsorbent fiber can be air laid or wet laid into alayer and combined with a nanofiber or other useful layers. In anotherexample, a super absorbent particulate can be used or used when blendedwith an inert particulate for use in such a layer.

The inert particulate can comprise a single particulate or can be ablend of inert particulate that differs by composition particle size,particle morphology or some other particle aspect. Similarly, the superabsorbent particulate can comprise a mixture of particulates includingdifferent active particulates. For example, a super absorbent materialcan be used with a carbon particulate or could be blended with a zeoliteparticulate. Alternatively, a carboxy methyl cellulose particulate canbe blended with an ion exchange resin particulate in an active layer.Further, such active particulate can have a blended particulate in thesense that particulates of different size, shape or methodology can becombined in the active layers of the invention. The term “entrainedparticulate” refers to impurities in the mobile fluid while the term“dispersed particulate” refers to the particulate deliberately includedwithin the fiber layers of the invention.

The web of the invention can be used in one of two separate modes. Thesemodes are designated as “flow-through” or “flow-by”. A single unit canhave regions of both modes. In the flow-through mode, the mobile fluid,liquid or gas, passes through the nanofiber layer and substrate in afiltration mode with at least a portion of the flow path as a flowsubstantially normal to the plane of the fiber layer. Such a flow pathcan have a tortous route but when contacting the layer is at or near anormal orientation. The entrained particulate can encounter and beremoved by the element and as the fluid passes through the layers incontact with the particulate, the particulate can react with absorbed oradsorbed chemical materials suspended or dissolved in the fluid.

In the flow-by mode, the fluid path is generally parallel to the planeof the nanofiber layer or element surface. In the flow-by mode, flow canbe turbulent but the fluid typically contacts the surface of the layerat it flows past the layer and does not substantially flow through theelement. While depending on viscosity, flow rate, turbulence,temperature, element configuration, the fluid can to some degreepenetrate the layer and can flow from layer to layer, the primary modeof transport of the fluid is bypassing the layer in a directionsubstantially parallel to the layer's surface. In such a mode, theliquid can contact the surface of the layer and chemical materialsdissolved and suspended in the fluid can react with, be absorbed, oradsorbed by the particulate.

The flow-through and flow-by element can be used in a variety offormats. Flow-through element can be used in conventional filterstructures including cartridge panel in some other filter structures,with the element in a pleated or unpleated mode. Similarly, the flow-bymedia can be included in the panel and cartridge structures.

One preferred mode of use of either flow through or flow-by material isin a rolled media. Rolled media are prepared by first forming thenanofiber and SAP fabric or SAP particulate layer on a substratepreferably a filter substrate. The combined materials can be heattreated if needed. The web and substrate can be rolled into amulti-layered roll having (e.g.) 2 to 50 layers. The thickness of theroll, or a separation between the layers, determines the flow rate offluid through the structure. The flow rates can be improved byintroducing channels into the rolled media.

Such channels can be preformed in the substrate upon which the nanofiberis spun, or the channels can be formed into the element after thenanofiber layer is formed on the substrate and then heat treated ifnecessary. Mechanical forms or spacers can be included with theprocessing steps. The forms or spacers can introduce the channel intothe structure. At least one spacer portion can be included with therolled material to inherently form a channel in one portion of therolled structure. Further, additional spacers can be placed such thateach layer of the rolled structure has at least one channel portion. Anarbitrary number of spacers can be used. At least one spacer per layercan be used up to 5, 10 or 20 spacers per layer. After the spacer layersform a channel in the element, the spacers can be removed. The spacerscan be removed in one mode by unrolling the element and physicallyremoving the spacers from the element. However, in another mode, thespacers can be simply washed from the rolled assembly using a solvent inwhich the spacer (but not the substrate nanofiber or particulate) issoluble, thus removing the spacers and leaving flow-through channelstructures. The spacers can be configured in virtually any shape orstructure as long as the spacer can provide a channel from the first endof the roll to the second end of the roll providing a flow through pathfor fluid.

Preferably the dimensions of the channel are greater than about 1 mm inmajor dimension and can range from about 1 to 500 mm in major dimension.The profile of the channels can be round, oval, circular, rectangular,square, triangular, or other cross-sectional profile. The profile can beregular, or it can be irregular and amorphous. Further along thechannel, the cross-sectional profile of the channel can vary from oneend to the other. For example, at the intake end of the rolledstructure, the channel can have a relatively large cross-sectional area,whereas at the opposite end the cross-sectional area can be smaller thanthe input end. Additionally the input end can be smaller incross-sectional area than the output end. Any other variation in size ofthe spacer can increase turbulence in the flow resulting in improvedcontact between the fluid and the particulate.

The filter or flow-through or flow-by structure of the invention isuniquely suited to provide useful properties. The flow-through structurecan be used to absorb/adsorb or chemically react with mobile fluidphases that flow through the flow-through structures. The dispersedparticulate within the flow-through structures can react with the mobilefluid (either liquid or gas), or absorb/adsorb, or react withintervening material within the fluid stream. The flow-throughstructures can act both as a filter, and as a structure that can reactwith, absorb, or adsorb materials in the fluid stream. Accordingly, thedual function flow-through structures can remove undesired particulatethat is typically an insoluble phase in the fluid stream. In addition,the flow-through structures can also react with, absorb, or adsorbinsoluble and soluble components of the fluid stream.

A particularly important fluid stream for the application includes airstreams that can contain contaminates such as dust particulate, aqueousmist or humidity, solvent residue, oil residue, mixed aqueous oilresidue, harmful gases such as chlorine, benzene, sulfur dioxide, etc.Other typical liquid mobile phases include water, fuel, oils, solventstreams, etc. Such streams can be contacted with the flow-throughstructures of the invention to remove liquid or particulatecontaminates, color-forming species, and minor amounts of solubleimpurities. In many cases, the streams (both gaseous and liquid) can becontaminated by biological products including prions, viruses, bacteria,spores, DNA segments and other potentially harmful biological productsor hazardous materials. Typically water can be a contaminant inhydrocarbon and other nonaqueous streams while hydrocarbons can be acontaminant in an aqueous stream.

The web of the invention can contain the nanofiber layer with the superabsorbent fabric, particulate or fiber dispersed within or formed on orcombined with the nanofiber layer, optionally with another particulateto absorb/adsorb or react with materials entrained in the mobile fluidphase. Such an element or web can be combined with other active orreactive species in a variety of forms.

The superabsorbent fabric can be formed of super absorbent fiber or canbe made with mixed or blended conventional fiber and super absorbentfiber. The fibers can be combined in a single layer or formed intodiscrete layers. The fabrics can be made of the select fibers usingweaving or air laid, wet laid or other nonwoven techniques.

The particulate of the invention can be discrete particles separate fromthe fiber or the particulate can be adhered to or on the surface of thefiber. The particulate can be embedded into the fiber and can bepartially or fully surrounded by the fiber mass. In order to form thesestructures, the particulate can be combined with the fiber afterspinning, can be added to the fiber during spinning in the time thefiber dries and solidifies, or can be added to the spinning solutionbefore spinning such that the particulate is embedded partially or fullyin the fiber.

One method of forming a useful layer can be by dispersing the superabsorbent particulate or fiber in an aqueous or non-aqueous phasecontaining components, either forming the active particulate into asheet layer followed by fiber, or adhering the active particulates toone or more of the components of the web or element of the invention.Any of the active particulates of the invention can be incorporated intoeither an aqueous or non-aqueous liquid phase for such purposes. Informing the non-aqueous material, a non-aqueous solvent, preferably avolatile solvent including such materials as lower alcohols, ethers, lowboiling hydrocarbon fractions, chloroform methylene chloride, dimethylsulfoxide (DMSO) and others, can be prepared by incorporating the activeparticulate of the material with soluble or dispersible bindingmaterials. Such a solution can be applied to a fiber particulate sheetlike substrate or other materials to form a layer containing the activeparticulates that can act in that form to absorb/adsorb or react withmaterials entrained in the mobile fluid phase. Alternatively, the SAP orfiber or optional active particulate of the invention can be dispersedin an aqueous solution or suspension of binding materials that can besimilarly combined with, or coated on, fiber particulate or web sheetlike substrates to form an active layer of active particulate.Alternatively, the active particulate of the invention can be dispersedor suspended in a mixed aqueous organic phase that combines an aqueousphase with organic phase. The organic phase can comprise additionalsolvents or other organic liquids or can comprise aqueous polymericphase such as acrylic polymers, PTFE polymers. Such mixed phases canform layers containing the active particulate and additionally cancontain cross-linking components that can form bonds between adjacentpolymers, further curing the coatings of films.

A heat treatment or thermal bonding process can be used to form adistinct layer in which there is no fully distinct fiber. Such atreatment can be used with any construction with thermoplastic fiber.Such layers can include the SAP or the superabsorbent fiber materials.The heat treatment can heat the individual fibers to a temperature at orabove a fusion or melting point of the individual fibers and then causethe fibers to adhere, coalesce, or form into a fused network, membraneor membrane-like structure. Depending on the temperature and pressureand time of the heat treatment, the heat treatment can convert thefibers from a randomly distributed layer of fiber of intermediate lengthhaving only surface contact into a layer where fibers are moreintimately associated. At a minimum, the fiber is heated such that atthe intersections of the fibers, the fibers fuse to form a fusednetwork. With additional heat pressure, or time of heat treatment, thefibers can further melt and further coalesce into a more intimatelyassociated web. With further temperature, time, and pressure, the fibercan more fully melt and spread into a porous membrane-like structure.The heat treatment also can alter the location of the super absorbentparticulate or fiber or other particulate. In the instance that thefiber is simply distributed throughout, the particulate is distributedthrough the nanofiber. The heat treatment can fix the super absorbentparticulate or fiber into a structure in which the particulate issurface bonded to the heat treated fibrous, web, or membrane-likestructure; however, depending again, on the temperature, time ofheating, and pressure, the particulate can be incorporated into andthroughout the porous membrane-like structure. Such a heat treated orcalendared structure can have a layer of thickness that approximatesthat of the original nanofiber layer, or results in a layer that isthinner than the original nanofiber layer. Accordingly, if the originalnanofiber layer has a thickness that ranges from about 0.5 to 200microns, the resulting layer can have a thickness that ranges from about0.5 to about 150 microns or smaller often up to 100 microns andsometimes up to 50 microns, depending on the amount of fiber spun, theparticulate content and the degree of heat treatment, including heating,pressure, and time. One form of such a heat treatment process is thecalendaring operation that can be used thermally. The calendaringprocess uses rollers, rollers and embossers, or embossers to form theheat treated layers. An embosser can be used with a bonding pattern thatcan result in a regular, intermediate, or random pattern. When a patternis used, the pattern can occupy up to 50 percent of the surface area ormore. Typically, the bonded array occupies about 1 to 75 percent of thesurface area, often about 10-50 percent of the surface area.

Depending on the nature of the nanofiber used in the various layers andthe rate of manufacture of the composites, the calendaring processparameters such as time, temperature, and pressure can be varied toachieve acceptable results. The temperature of the calendared rollerscan range from about 25-200° C. The pressure exerted on the layers usingthe calendaring rollers or combination of rollers can range up to 500psi and the speed of the composite through the heat treatment stationcan range from about 1 to about 500 feet per minute. The operatingparameters of the heat treatment station must be adjusted such that theappropriate amount of heat is delivered to the fiber to obtain thecorrect ultimate structure. The heat cannot be so little as not tosoften or melt some portion of the fiber and cannot be such that thefiber is simply melted and dispersed into the substrate. The total heatdelivered can be readily adjusted to bond the fiber, soften the fiberoverall or fully form the fibers into a porous membrane. Such minoradjustment of the operating parameters is well within the skill of theartisan.

The web or element of the invention can be comprised of a variety ofdifferent layers. Such layers can include both active and inactivelayers. Active layers typically comprise a web of nanofiber with thesuper absorbent particulate, super absorbent fiber or super absorbentfabric combined with or dispersed within the nanofiber or otherimpregnated layers or layers containing super absorbent particulate,fiber fabric or other adsorbent/absorbent or reactive particulate orother such structures. A super absorbent material is one that can absorba greater amount of water than it weight, such as, at least 10 grams ofwater per gram, or 20 to 100 grams of water per gram of material. Suchlayers can be formed into the useful element of the invention combinedwith protective layers, spatial layers, active layers, inactive layers,support layers, and all can be incorporated or encapsulated intoconventional cartridge panel or other such protective structures. Apreferred form of the active particulate comprises an adsorbent carbonparticulate.

In one embodiment of the invention, a superabsorbent nonwoven layer iscombined with a nanofiber layer. In a second embodiment a superabsorbentlayer has a nanofiber layer formed on each side of the planar layer.These embodiments can be used with filter layers that can filter solidparticulate in coarse particle sizes (about 10 to 50 microns) or fineparticulate (about 1 to 10 microns). Such layers can be formed on aperforate core structure. Such core can be cylindrical molded grid likeplastic structures. Such cores can be used with other screen and supportmaterials.

There are a variety of types of superabsorbent polymers (SAP) that canbe used in particulate, fiber or fabric form. Such materials includestarch-graft polymers, acrylic or cross-linked polyacrylatespolyacrylamide, poly (ethylene oxide), poly (vinyl alcohol),polysuccinimides, and hydrolyzed polyacrylonitrile polymers. Preferredtypes of superabsorbent polymers are starch-graft polymers, acrylic orcross-linked polyacrylates. As used herein and unless otherwisespecified the term “super-absorbent particle or fiber” means a particleor fiber made from a super-absorbent polymer or comprising asuper-absorbent material. Specific super-absorbent particle or fiber arefibers made from super-absorbent polymers. Specific super-absorbentparticle or fiber are substantially free (e.g., contain less than about50, 10, 5, 1, or 0.5 weight percent) of materials that are notsuper-absorbent. These super absorbent materials in particle, fiber orfabric swell to form gels. Most super-absorbent polymers currently usedare sodium acrylate-based polymers which have a three dimensionalnetwork-like molecular structure. Small amounts of crosslinkers play amajor role in modifying the properties of superabsorbent polymers. Thetype and quantity of crosslinkers control both the swelling capacity andgel modulus. Other suitable water swelling materials are natural-basedsuper-absorbent fibers such as, but not limited to, crosslinkedpolysaccharides or modified cellulose products. Still othersuper-absorbent materials that can be used to provide fibers useful inparticular embodiments of this invention are described below, as arevarious fabric forms of such fibers.

Super-absorbent particle or fiber can be made from ethylenicallyunsaturated carboxylic monomers and copolymerizable ethylenicallyunsaturated monomers. These fibers are formed by extruding a solution ordispersion of the polymeric material in a solution of the secondarymatrix copolymer in its non-crosslinked state into a gaseous environmentwherein solvent is removed to form the fiber, and subsequentlycrosslinking the matrix copolymer. See e.g., U.S. Pat. Nos. 5,466,733and 5,607,550, and European patent application 26 84 98, each of whichis incorporated herein by reference for teaching of superabsorbentmaterials. This technology has been used by Oasis Technical AbsorbentsLtd, UK and Camelot (Canada). One example of fibers made by this methodare fibers of polysodium acrylate. Another example of super-absorbentfibers that can be used in this invention are core/sheath structurebicomponent fibers, wherein the sheath is an outer layer of hydrolyzedpolyacrylonitrile salt, such as, but not limited to, polysodium acrylateor polyammonium acrylate, and the core is polyacrylonitrile. Examples ofsuch fibers include LANSEAL F, (Toyobo, Japan), which has a core made ofacrylic fiber and a sheath made of polyacrylate superabsorbent. Inspecific fibers, the outer layer swells to about 12 times in diameter byimbibing water. The polymer can contain substituents, such as alkyl,such that functional moieties bound to the polymer include, but are notlimited to, ammonium acrylate, acrylic acid, and un-hydrolyzedacrylonitrile. Specific examples of bicomponent media that can be madewith and without the superabsorbent particles or fiber are shown in U.S.Pat. No. 7,314,497 which is specifically incorporated by referenceherein for its teaching of media with fused bicomponent fibers.

Other super-absorbent fibers that can be used in the invention are madeof thermoplastic polymeric fibers and super-absorbent particles, whichcan be attached to the thermoplastic fibers by thermobonding. Forexample, they can be bonded by heating the polymeric fiber to atemperature at which adhesion is obtained between the fiber and thesuper-absorbent particles. See, e.g., U.S. Pat. No. 6,194,630, which isincorporated herein by reference.

Another type of super-absorbent fiber comprises partially hydrolyzed,internally plasticized, crosslinked, superabsorbent fibers derived frompolysuccinimide fiber. See, e.g., U.S. Pat. Nos. 6,150,495 and5,997,791, both of which are incorporated herein by reference for itsteaching of super absorbent materials. The crosslinked hydrolyzedpolysuccinimide fibers are made of polyamide containing at least threedivalent or polyvalent moieties distributed along the polymer chain.

Other super-absorbent materials that can be used in various embodimentsof this invention are disclosed in European patent application 43 78 16,which is incorporated herein by reference. These fibers are provided asa nonwoven wet-laid superabsorbent material produced by the process ofblending superabsorbent polymer particles, and drying the superabsorbentslurry/fiber mixture to form a nonwoven wet-laid superabsorbentmaterial.

Specific examples of super-absorbent materials that can be provided asparticle or fiber and used in various embodiments of this inventioninclude, but are not limited to, hydrolyzed starch acrylonitrile graftcopolymer; neutralized starch-acrylic acid graft copolymer; saponifiedacrylic acid ester-vinyl acetate copolymer; hydrolyzed acrylonitrilecopolymer; acrylamide copolymer; modified cross-linked polyvinylalcohol; neutralized self-crosslinking polyacrylic acid; crosslinkedpolyacrylate salts; neutralized crosslinked isobutylene-maleic anhydridecopolymers; and salts and mixtures thereof.

Other super-absorbent materials that can be used in the inventioninclude, but are not limited to, those disclosed by U.S. Pat. Nos.6,433,058; 6,416,697; 6,403,674; 6,353,148; 6,342,298; 6,323,252;6,319,558; 6,194,630; 6,187,828; 6,046,377; 5,998,032; 5,939,086;5,836,929; 5,824,328; 5,797,347; 5,750,585; 5,175,046; 4,820,577;4,724,114; and 4,443,515, each of which is incorporated herein byreference for its teaching of super absorbent materials. Additionalexamples include, but are not limited to: treated polyacrylonitrilefibers (e.g., fibers treated with metal hydroxides or ammonia);crosslinked partially neutralized maleic anhydride copolymer spunfibers; polyacrylonitriles co-spun with superabsorbent polymers such asacrylate/acrylonitrile copolymers; crosslinked polyacrylate andcopolymer fibers, such as those described in Japanese Patent No.89/104,829, which is incorporated herein by reference; fiber flockscontaining super-absorbents as described in U.S. for its teaching ofsuper absorbent materials U.S. Pat. No. 5,002,814, which is incorporatedherein by reference; and polyoxyalkylene glycol fibers, such as thosedescribed in U.S. Pat. No. 4,963,638, which is incorporated herein byreference for its teaching of super absorbent materials. Natural-basedsuperabsorbent fibers such as, but not limited to, crosslinkedpolysaccharides and modified cellulose products can also be used incertain embodiments of the invention, as can cellulosic-basedsuperabsorbents. Examples of preferred super-absorbent fibers areLANSEAL (Toyobo, Japan); N-38 type 101, type 102, type 121 and type 122(Oasis Technical Absorbents, UK); and Camelot 808, 908, and FIBERSORB(Arco Chemicals).

The selection of super-absorbent material(s) for use in a material ofthe invention will depend on a variety of factors, including thephysical and chemical properties of the superabsorbent material and itsuse in a gaseous or liquid application. For example, factors to beconsidered when selecting a super-absorbent material include, but arenot limited to, the amount of water it can absorb, its rate of waterabsorption, how much it expands when it absorbs water, its solubility innon-aqueous solvents with which it may come into contact, its thermalstability, and its biocompatibility.

The physical and chemical properties of a super-absorbent materialdepend, at least in part, on the physical and chemical properties of thespecific molecules from which it is made. For example, the bulkproperties of a super-absorbent material made from a particular polymercan depend on the average molecular weight and hydrophilicity of thatpolymer. The bulk properties of the super-absorbent material can furtherdepend on the amount and type of crosslinking that holds the polymerstogether.

Crosslinking can be of at least two types, and mixtures thereof. A firsttype is covalent crosslinking, wherein polymers are covalently attachedto one another by methods well known in the art. A second type isphysical crosslinking, wherein polymers are associated by hydrogenbonding, ionic bonding, or other non-covalent interactions, which canprovide crystalline or semi-crystalline super-absorbent materials.Super-absorbent materials that are covalently crosslinked are typicallymore durable than physically crosslinked materials, but often containchemical residues from the crosslinking process. Consequently,chemically crosslinked super-absorbent materials may not be suitable foruse in applications wherein the leaching of such residues must beavoided. The preferred materials are highly crosslinked and have noeasily measured molecular weight.

The durability and toughness of super-absorbent materials typicallyincrease with increased crosslinking. However, the ability ofsuper-absorbent materials to rapidly expand and absorb water candecrease with increased covalent crosslinking. For example, sodiumpolyacrylate-based super-absorbent materials contain long, interwovenpolymer chains having a number of ionic functional groups. Whencontacted with water, the ionic functional groups disassociate toprovide an ionized polymer network. Swelling of the material occurs asionic crosslinking is eliminated, and is accelerated due to repulsionsbetween anions bound to the polymeric chain. As the material swells,large void volumes are created, which can accommodate the absorption ofwater until the polymer matrix can no longer expand. The scale ofexpansion is determined, at least in part, by the degree ofcrosslinking. Without intermolecular crosslinking, super-absorbentmaterials would expand infinitely; i.e., they would dissolve.

The degree to which a super-absorbent material absorbs water is relatedto the concentration of ionic functional groups and crosslinking densityin it. In general, water absorption increases with an increasedconcentration of ionic functional groups and/or a decrease incrosslinking density. Of course, when particles or inclusions ofsuper-absorbent material are trapped within the porous matrix of aself-sealing material, their expansion is also restricted by the matrixsurrounding them.

Although starch-graft polymers were the first developed, these polymerssuffer from the disadvantage of salt instability. Polyacrylate polymersinitially had difficulty achieving high absorption under load (AUL)characteristics at moderate pressures, as the materials would partiallydissolve. However, this problem was solved by partly cross-linking thepolyacrylate to provide a networked structure.

The sodium acrylate and starch-graft polymers account for virtually allof the commercial volume of super absorbent polymers, and are the focusof this report. Thus, sodium acrylates are expected to remain thecommercially preferred SAP material. Starch-grafted polymers wereoriginally developed by the United States Department of Agriculture andpatents were licensed to General Mills Inc. among others. This polymeris prepared by graft-polymerizing acrylonitrile onto a starch substrateto give the type of structure shown:

The polymerization reaction is as follows:

Ammonium ceric nitrate has been used as an initiator with 0.1 molecerium ions in one normal nitric acid. Optimal results are obtained whenstarch is gelatinized by heating in water at 80° C. for an hour prior tothe reaction, which occurs at around 30° C. and atmospheric pressure.Gelatinization breaks down the starch chains giving increased reactivitywith the acrylonitrile and a higher molecular weight product.Saponification of the graft polymer with an alkali yields a finalproduct with nitrile, amide, and carboxyl functionalities. The reactionis shown on the next page.

The saponification reaction takes place at 95° C. and atmosphericpressure with a ratio of alkali to acrylonitrile of 0.6-0.8 to 1 forsaponification. Washing with water removes excess salts produced duringsaponification. Acrylonitrile was used originally; acrylic acid monomer,which is nontoxic, is now preferred. After this reaction, drying andpulverization give a white powder.

Polyacrylate SAPs involve the copolymerization of acrylic acid, sodiumacrylate, and a cross-linking agent to provide a minimally cross-linkedpolymer containing carboxyl and sodium carboxylate groups. The basicreaction chemistry is shown in the following:

Cross-linking during polymerization is important in that it yields anetworked polymer, which will not dissolve in water, and can absorb andretain water under low load. A typical cross-linking agent istrimethylolpropane triacrylate in concentrations of 0.05 mol percentrelative to the monomer. Cross-linking is also possible with ethyleneglycol diglycidyl ether which reacts with carboxyl groups on the polymermolecules to crosslink them.

Controlling molecular weight of the polymer product is important inorder to balance performance versus yield. Low molecular weight speciesare extractable, whereas high molecular weight species require a longerpolymerization time. Commercial superabsorbent polymers typicallycontain between 5 and 20 percent extractables.

To carry out the polymerization, an acrylic acid solution is neutralizedwith sodium hydroxide to a level of 65-80 mol percent to provide a pHcompatible with human skin:

CH₂═CH—COOH+NaOH→CH₂═CH—COONa+H₂O

Thereafter, the polymerization is carried out at 30-45 weight percent ofthe monomers in aqueous solution at 75° C. and atmospheric pressure. Atypical initiator for the acrylic polymer polymerization is2,2,1-azo-bis-(2-amidinopropane) dihydrochloride. After the reaction,the material is removed, dried, ground to a fine powder, and treatedwith additional curing agent. The additional curing step is designed toyield a superabsorbent particle with a cross-linked “shell”. The purposeof the shell is to better control swelling of the superabsorbentparticle. There is a tendency of superabsorbent particles to form clumpswhen aqueous liquids are added, thereby reducing the diffusion ofadditional liquid through the partially swollen mass. Surfacecross-linking of the particles controls surface swelling, thus reducingclumping.

The optional particulate materials of the invention have dimensionscapable of improving the active properties and filtration properties ofthe media and layers of the invention. The materials can be made of avariety of useful materials that are inert, reactive, absorptive, oradsorptive. The materials can either be substantially inert to themobile phase and entrained particulate load passing through the web orthe materials can interact with the fluid, dissolved portions of thefluid or the particulate loading in the fluid. Some or all of theparticulate can be inert. Preferred particulates are active, reactive,absorbent, or adsorbent materials. For the purpose of this invention,the term “inert” indicates that the material in the web does not eithersubstantially chemically react with the fluid or particulate loading, orsubstantially physically absorb or adsorb a portion of the fluid or theparticulate loading onto the particulate in any substantial quantity. Inthis “inert” mode, the particulate simply alters the physical parametersof the fiber layer and the media including one or more fiber layers. Theactive particulate of the invention can be added to any layer of theelement of the invention using a variety of add on techniques. Theparticulate of the invention can be incorporated into the nanofiberlayer during spinning of the fiber as discussed elsewhere in theapplication. In addition, the active particulate of the invention can bedissolved or dispersed into an aqueous or nonaqueous or mixed aqueousliquid and applied to any layer of a useful element of the invention.

When using an active particulate that interacts with the fluid or theparticulate loading, the particulate can, in addition to altering thephysical properties of the media or layers, react with or absorb oradsorb a portion of either the mobile fluid or the particulate loadingfor the purpose of altering the material that passes through the web.The primary focus of the technology disclosed herein is to improve thetreatment properties of the layers to increase thereactivity/absorbent/adsorbent capacity or lifetime of the physicalstructure of the media or layers, and to improve filter performancewhere needed. In many such applications, a combination of an inertparticle and an interactive particle will then be used.

The invention relates to polymeric compositions in the form of nanofibersuch as microfibers, nanofibers, in the form of fiber webs, or fibrousmats used with a particulate in a unique improved filter structurecontaining the super absorbent particulate or fiber. The web of theinvention comprises a substantially continuous fiber phase and dispersedin the fiber mass a super absorbent particulate or fiber. In the variousaspects of the invention, the super absorbent particulate or fiber cancomprise a fiber or particulate phase in the web. The super absorbentparticulate or fiber can be found on the surface of the web, in surfaceproducts or throughout void spaces formed within the web. The fibrousphase of the web can be formed in a substantially singular continuouslayer, can be contained in a variety of separate definable layers or canbe formed into an amorphous mass of fiber having super absorbentparticulate or fiber inclusion phases throughout the web randomlyforming inclusion spaces around the particulate and internal websurfaces. The super absorbent particulate or fiber has a major dimensionof less than about 5000 microns. For example, the super absorbentparticulate or optional particulate can have a major dimension of lessthan 200 microns, and can typically comprise about 0.05 to 100 micronsor comprises about 0.1 to 70 microns. In the substantially continuousnanofiber layer, the layer has a layer thickness of about 0.0001 to 1cm, 0.5 to 500 microns, about 1 to 250 microns, or about 2 to 200microns. In the layer, dispersed in the fiber, is a means comprising anSAP or optional particulate with a particle size of about 0.25 to 500microns, about 0.5 to 200 microns, about 1 to 200 microns about 10 to200, or about 25 to 200 microns. Such particulate is dispersedthroughout the fiber in the layer. The particulate is present in anamount of about 0.1 to 50 vol %, about 0.5 to 50 vol %, about 1 to 50vol %, about 5 to 50 vol % or about 10 to 50 vol %. The fine fiber has adiameter of about 0.001 to about 2 microns, 0.001 to about 1 micron,0.001 to about 0.5 micron, or 0.001 to about 5 microns. The fiber can beof indeterminate length or have a fiber length of 0.1 to 10 cm, 0.2 to 7cm or 0.5 to 5 cm. The super absorbent particulate or fiber or optionalparticulate or combinations thereof is used in the layer in amount ofabout 1 to 1000 gm-m⁻², about 5 to 200 gm-m⁻² or about 10 to 100 gm-m⁻²of the layer.

The SAP and optional particulate can take a variety of regular geometricshapes or amorphous structures. Such shapes can include amorphous orrandom shapes, agglomerates, spheres, discs, ovals, extended ovals,cruciform shapes, rods, hollow rods or cylinders, bars, threedimensional cruciform shapes having multiple particulate forms extendinginto space, hollow spheres, non-regular shapes, cubes, solid prisms of avariety of faces, corners and internal volumes. The aspect ratio of thenon-spherical particulate (the ratio of the least dimension of theparticle to the major or largest dimension) of the invention can rangefrom about 1:2 to about 1:10, preferably from about 1:2 to about 1:8.

The optional particulate of the invention can be made from both organicand inorganic materials and hybrid. The particulate that isnon-interacting with the mobile fluid or entrained particulate phasecomprises organic or inorganic materials. Organic particulates can bemade from polystyrene or styrene copolymers expanded or otherwise, nylonor nylon copolymers, polyolefin polymers including polyethylene,polypropylene, ethylene, olefin copolymers, propylene olefin copolymers,acrylic polymers and copolymers including polymethylmethacrylate, andpolyacrylonitrile. Further, the particulate can comprise cellulosicmaterials and cellulose derivative beads. Such beads can be manufacturedfrom cellulose or from cellulose derivatives such as methyl cellulose,ethyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, andothers. Further, the particulates can comprise a diatomaceous earth,zeolite, talc, clay, silicate, fused silicon dioxide, glass beads,ceramic beads, metal particulates, metal oxides, etc. Particulatesintended for use in the present invention are characterized by averagesize in the range of from about 0.01 to 500 microns. Therefore, arelatively larger average size of the active particles requires a largeraverage size of the particulate. Particles include carbon particles suchas activated carbon, ion exchange resins/beads, zeolite particles,diatomaceous earth, alumina particles such as activated alumina,polymeric particles including, for example, styrene monomer, andabsorbent particles such as commercially available superabsorbentparticles. Particularly suitable absorbent/adsorbent particles are lowdensity, porous particles, and have pores and cavities including surfacecavities, ranging in diameter from about the minimum for the pore sizein carbon is 0.00035 microns, which is the carbon-carbon distance to 100microns and interconnected by smaller pores. These pores and cavitiesbeneficially provide inner surface for deposition, in particularmonolayer deposition, of fine particles having an average size in therange of about 0.01 to 10 microns, and thereafter for accessibility tothe immobilized fine particles. 1 cm³ of these particles provides inbulk approximately 75 to 1,500 m² of available surface. Carbonparticulates can be used in the form of filing divided activated carbon.Such activated carbons can be combined with other reactive adsorbent oradsorbent species that can be blended with, or adsorbed onto, the carbonsurface. Other forms of active carbon can be used including carbonnanotubes, nanoparticles, nanowires, nanocarbon ropes or larger latticesor constructs in which the individual elements comprise a carbonnanotube. Such nanoparticles, such as buckyballs, smaller nanotubes (ornanotube portions thereof), nanoropes, etc. can be incorporated withinthe interior volume of the nanotube or incorporated into the carbon atomlattice of the nano structure. Additional atoms, molecules or componentscan add structure or function to the nano particulate material.

The SAP or optional particulate can be mono-disperse or poly-disperse.In mono-disperse particulate, the majority of the particles are similarin diameter or the major dimension. For example, one example of amono-disperse particulate has 80% to 90% of the particulate within about0.8±0.5 microns or about 1±0.25 micron. In a poly-disperse material, theparticulate has a substantial portion of particles with differentdiameters. A poly-disperse material could be a mixture of twomono-disperse materials or a material with a substantial amount ofparticulate material present throughout a broad range (e.g.) 0.1 to 10or 0.01 to 100 microns.

The spheres or other shapes can be in a variety of different physicalforms including solid and hollow form. The particulate can have asubstantially spherical or slightly oval shaped spherical structure. Thespheres can be solid or can have a substantial internal void volume. Theshell thickness of the sphere can range from about 0.05 to about 500microns while the sphere can range from about 0.5 to about 5000 microns.Other circular structures that can be used include simple toroidalstructures, spiral or helical structures, or interlocking link typechain structures.

The web can also be used in filtration applications as a surface mediaor depth media having a continuous web of nanofiber modified by thepresence of super absorbent particulate, fiber or fabric and theoptional a reactive, absorptive or adsorptive spacer or separation meansin the form of a particulate that in combination with the fiber in themedia, provides figure of merit, filtration efficiency, filtrationpermeability, depth loading and extended useful lifetime characterizedby minimal pressure drop increase. The super absorbent particulate,fiber or fabric and reactive, absorptive, or adsorptive spacer orseparation means causes the fiber web to attain a structure, in whichthe fiber mass or web portion has reduced solidity, separated fibers orseparated web portions within the structure, and increased depth offiber layer, without increasing the amount of polymer or the number offibers in the web. The reactive, adsorptive or absorptive, portion ofthe fiber web can react with reactive chemical species within a mobilefluid passing through the fiber layer or such chemical components of themobile fluid can be absorbed or adsorbed by the absorptive or adsorptiveportion of the fiber layer. The super absorbent particulate or fiber oractive particulate can be used with an inert particulate as long as theactivity or activities of the particulate is maintained. The resultingstructure obtains improved filtration properties in combination withresistance to increased pressure drop, improved (Figure of Merit,)improved permeability, improved efficiency, and the ability to removeboth a particulate non-reactive load and a reactive gaseous orparticulate load from a mobile fluid stream passing through the fiberlayer.

The nanofiber of the invention can be in the form of a structural fiberas discussed above. The nanofiber can be spun from a reactive fiber orsuper absorbent particulate or fiber. Such reactive fibers can be madefrom polymers having reactive side chains such as amines, sulfonic acid,carboxylic acid, or other functional groups of side chains. Such sidechains can be derived from the polymer itself. For example, a polyaminecan be formed with a highly functional polyamine leaving acid and amineand mean functionality on the polymer side chains of substituents.Similarly, polysulfone or polyacrylic acid material can be formed havingactive or reactive acid groups. Similarly, ion exchange resin materialscan be made having, within the resin particulate, acid, strongly acid,basic, or strongly basic functional groups that can add absorbent orreactive properties to the invention. Such materials can be dissolved orsuspended and can be spun with the conventional fibers of the invention,or can be spun separately into the particle containing webs of theinvention.

The web can be spun in such a way to disperse the super absorbentparticulate or fiber or active particulate or active separation meansinto the fiber. A preferred super absorbent particulate or fiber oractive particulate or spacer means comprises a reactive, absorptive oradsorptive particulate. Such particulate can be dispersed within thepolymer containing solution. The particle or fiber can be added to theweb during formation or can be added after formation. Such a web, whenelectrospun, is characterized by a mass of interconnected nanofiber ornanofiber with the super absorbent particulate or fiber dispersed withinthe fiber web on the surface of the fiber web. Within the fiber web, thesuper absorbent particulate or fiber creates void spaces within theinterconnected fibrous structure that reduces solidity and increasesmobile fluid flow. The invention also comprises a web formed by forminga nanofiber mass with the simultaneous addition or a post spinningaddition of the super absorbent particulate or fiber to the fiber layer.In such an embodiment, the particle or fiber is interspersed throughoutthe mass of fibrous material. Lastly, the invention involves forming thespun layer in a complete finished web or thickness and then adding thesuper absorbent particulate or fiber to the surface of the web orsubstrate prior to incorporating the web into a useful article.Subsequent processing including lamination, calendaring, compression orother processes can incorporate the particulate into and through thefiber web. One advantage of either simultaneous addition of the superabsorbent particulate or fiber to the web as it is formed or to the webafter formation, is obtained when the particulate is a solvent solubleparticulate. Dissolving the soluble particle or fiber in the solutionwould result in the incorporation of the material into the fiber withoutmaintaining the particulate as a separate phase in the web. Adding theparticulate to the web after formation preserves the solvent solublematerial in its particulate form.

“Figure of Merit” can be thought of as a benefit to cost ratio, whereefficiency is the benefit, and normalized pressure drop (ΔP) is the cost(ΔP/media velocity). The “cost” is normalized so that one can compareFigures of Merit from tests run at different velocities. Figure of Meritis simply an index to compare media. Larger Figure of Merit values arebetter than small. The formula for calculating Figure of Merit is:

Figure of Merit=−Ln(penetration)/(ΔP/media face velocity)

In the equation presented above, ΔP is the pressure drop across themedia and the unit used in the equation is cm Hg; media face velocityhas the unit of cm/sec; Ln(penetration) is the natural logarithm ofpenetration. And penetration is defined as:

Penetration=1−Efficiency

The standard units of measure which Figure of Merit is reported in aregiven below:

1/(cm Hg)/(cm/sec) or (cm/sec)/cmHg

In many applications, especially those involving relatively high flowrates, an alternative type of filter media, sometimes generally referredto as “depth” media, is used. A typical depth media comprises arelatively thick tangle of fibrous material. Depth media is generallydefined in terms of its porosity, density or percent solids content. Forexample, a 2-3% solidity media would be a depth media mat of fibersarranged such that approximately 2-3% of the overall volume comprisesfibrous materials (solids), the remainder being air or gas space.

The nanofiber layers formed on the substrate in the filters of theinvention should be substantially uniform in particle or fiberdistribution, filtering performance and fiber distribution. Bysubstantial uniformity, we mean that the fiber has sufficient coverageof the substrate to have at least some measurable filtration efficiencythroughout the covered substrate. The media of the invention can be usedin laminates with multiple webs in a filter structure. The media of theinvention includes at least one web of a nanofiber structure. Thesubstrate upon which the nanofiber and active particulate can be formedcan be either active or inactive substrate. Such substrates can haveincorporated into the substrate layer active materials in the form ofcoatings, particulates, or fibers that can add adsorbent/absorbent orreactive properties to the overall structure.

The overall thickness of the fiber web is about 1 to 100 times the fiberdiameter or about 1 to 300 micron or about 5 to 200 microns. The web cancomprise about 5 to 95 wt.-% fiber and about 95 to 5 wt.-% particle orfiber or about 30 to 75 wt.-% particle or fiber and about 70 to 25 wt.-%super absorbent particulate or fiber occupies about 0.1 to 50 vol % ofthe layer or about 1 to 50 vol % or 2 to 50 vol % of the layer. Theoverall solidity (including the contribution of the active or inactiveparticulate) of the media is about 0.1 to about 50%, preferably about 1to about 30%. The solidity of the web without including the contributionof the particulate in the structure is about 10 to about 80%. The filtermedia of the invention can attain a filtration efficiency of about 20 toabout 99.9999% when measured according to ASTM-1215-89, with 0.78μmonodisperse polystyrene spherical particles, at 13.21 fpm (4meters/min) as described herein. When used in HEPA type application, thefilter performance is about 99.97% efficiency at 10.5 fpm and 0.3 micronNaCl or DOP particle size. Efficiency numbers in respect to this type ofefficiency testing (0.3 micron DOP at 10.5 fpm test velocity), yield anefficiency in the range of 20 to 99.9999%

The Figure of Merit can range from 10 to 10⁵. The filtration web of theinvention typically exhibits a Frazier permeability test that wouldexhibit a permeability of at least about 1 meters-minutes⁻¹, preferablyabout 5 to about 50 meters-minutes⁻¹ When used as a inactive particulateor separation means, the particulate that characterizes the particulatephase of the web of the invention is a particulate that is either inertto the mobile phase and the entrained contaminant load or has somedefined activity with respect to the mobile fluid or the load.

The nanofiber layers of the invention typically range from about 0.5 toabout 300 microns, 1 to about 250 microns or 2 to about 200 microns inthickness and contain within the layer about 0.1 to about 50 or 10 toabout 50 vol % of the layer in the form of both inert (if any) and thesuper absorbent particulate or fiber of the invention. In this case, thesuper absorbent particulate or fiber or active particulate of theinvention can be combined with inert spacer particulate in some amount.The active particulate of the invention acting to absorb, adsorb orreact with contaminants within the fluid flow while the inertparticulate simply provides an excluded volume within the layer toreduce solidity, improve efficiency and other filtration properties.

The creation of low pressure drop active particulate, chemicallyreactive, absorptive, or adsorptive substrates for the removal of gasphase contaminants from airstreams is from flat sheet rolls ofabsorptive/adsorptive/reactive media that are layered or rolled togetherwith a spacer media to form an adsorptive/reactive substrate with openchannels and absorptive/adsorptive/reactive walls. Additionally, thespacer media can be made to be absorptive/adsorptive/reactive so as tocontribute to the overall life/performance of the final chemical unit.The spacer media that creates the open channels can be created from amesh, single lines of a polymer bead, glue dots, metal ribs, corrugatedwire/polymer/paper mesh, corrugated metal/paper/polymer sheets, stripsof polymer, strips of adhesive, strips of metal, strips of ceramic,strips of paper, or even from dimples placed in the media surface. Thesespacer media can be made absorptive/adsorptive/reactive by coating themor extruding/forming them with/from absorptive/adsorptive/reactivematerials. The contaminated airflow is primarily directed along thechannel created by the spacer media. This air comes into contact withthe adsorptive/reactive media walls and/or spacer media and subsequentlybecomes adsorbed or reacted. The channel size and shape is controlled bythe shape and size of the space media. Examples include squares,rectangles, triangles, and obscure shapes that may be created by adotted pattern of polymer/adhesive. The chemistry of the walls andspacer media can be made specific to adsorb acidic, basic, and organicand water vapors, as well as several specific classes of compoundsincluding reactive carbonyl compounds, including formaldehyde,acetaldehyde and acetone.

The super absorbent particulate or fiber can be held together withadhesive or fibers to encapsulate, or simply hold, the particles and/oradditional scrim materials are attached to hold the reactive material inplace and minimize shedding of particles. The super absorbentparticulate or fiber can also be sandwiched between layers of scrim. Thescrim could help to produce the channels or space between the layers.This could be accomplished with a high loft scrim material that wouldgive the proper spacing as well as ability to hold super absorbentparticulate or fiber in the media. The super absorbent particulate orfiber can be held together or interspersed with fibers.

Secondary fibers can be used to make useful layers or combined withsuper-absorbent fibers to provide specific materials of the invention.Secondary fibers can be used for a variety of reasons such as, but notlimited to, lowering the cost of the final products, increasing theirwet and dry strength, and increasing their ability to prevent migrationof wet super-absorbent material. Secondary fibers can be staplemonocomponent fibers and/or staple bicomponent fibers. Examples ofmonocomponent fibers include, but are not limited to, polyethylene (PE),polypropylene (PP), polystyrene (PS), nylon-6, nylon-6,6, nylon12,copolyamides, polyethylene terephthalate (PET), polybutyleneterephthalate (PBT), copolyester (CoPET), and cellulose based fibers,such as rayon and Tencel. Examples of suitable bicomponent fibersinclude, but are not limited to, PE/PET, PP/PET, CoPET/PET, PE/Nylon,PP/Nylon, Nylon-6,6/Nylon-6.

Polymer materials that can be used as the nanofiber polymer compositionsof the invention include both addition polymer and condensation polymermaterials such as polyolefin, polyacetal, polyamide, polyester,cellulose ether and ester, polyalkylene sulfide, polyarylene oxide,polysulfone, modified polysulfone polymers and mixtures thereof.Preferred materials that fall within these generic classes includepolyethylene, polypropylene, poly(vinylchloride), polymethylmethacrylate(and other acrylic resins), polystyrene, and copolymers thereof(including ABA type block copolymers), poly(vinylidene fluoride),poly(vinylidene chloride), polyvinylalcohol in various degrees ofhydrolysis (80% to 99.5%) in crosslinked and non-crosslinked forms.Preferred addition polymers tend to be glassy (a Tg greater than roomtemperature). This is the case for polyvinylchloride andpolymethylmethacrylate, polystyrene polymer compositions or alloys orlow in crystallinity for polyvinylidene fluoride and polyvinylalcoholmaterials. One class of polyamide condensation polymers are nylonmaterials. The term “nylon” is a generic name for all long chainsynthetic polyamides. Typically, nylon nomenclature includes a series ofnumbers such as in nylon-6,6 which indicates that the starting materialsare a C₆ diamine and a C₆ diacid (the first digit indicating a C₆diamine and the second digit indicating a C₆ dicarboxylic acidcompound). Nylon can be made by the polycondensation of ε-caprolactam inthe presence of a small amount of water. This reaction forms a nylon-6(made from a cyclic lactam—also known as ε-aminocaproic acid) that is alinear polyamide. Further, nylon copolymers are also contemplated.Copolymers can be made by combining various diamine compounds, variousdiacid compounds and various cyclic lactam structures in a reactionmixture and then forming the nylon with randomly positioned monomericmaterials in a polyamide structure. For example, a nylon 6,6-6,10material is a nylon manufactured from hexamethylene diamine and a C₆ anda C₁₀ blend of diacids. A nylon 6,6-6,6,10 is a nylon manufactured bycopolymerization of ε-aminocaproic acid, hexamethylene diamine and ablend of a C₆ and a C₁₀ diacid material.

Block copolymers are also useful in the process of this invention. Withsuch copolymers the choice of solvent swelling agent is important. Theselected solvent is such that both blocks were soluble in the solvent.One example is a ABA (styrene-EP-styrene) or AB (styrene-EP) polymer inmethylene chloride solvent. If one component is not soluble in thesolvent, it will form a gel. Examples of such block copolymers areKraton® type of styrene-b-butadiene and styrene-b-hydrogenatedbutadiene(ethylene propylene), Pebax® type of ε-caprolactam-b-ethyleneoxide, Sympatex® polyester-b-ethylene oxide and polyurethanes ofethylene oxide and isocyanates.

Addition polymers like polyvinylidene fluoride, syndiotacticpolystyrene, copolymer of vinylidene fluoride and hexafluoropropylene,polyvinyl alcohol, polyvinyl acetate, amorphous addition polymers, suchas poly(acrylonitrile) and its copolymers with acrylic acid andmethacrylates, polystyrene, poly(vinyl chloride) and its variouscopolymers, poly(methyl methacrylate) and its various copolymers, can besolution spun with relative ease because they are soluble at lowpressures and temperatures. However, highly crystalline polymer likepolyethylene and polypropylene require high temperature, high pressuresolvent if they are to be solution spun. Therefore, solution spinning ofthe polyethylene and polypropylene is very difficult. Electrostaticsolution spinning is one method of making nanofibers and microfiber.

The polyurethane (PU) polyether used in this layer of invention can bean aliphatic or aromatic polyurethane depending on the isocyanate usedand can be a polyether polyurethane or a polyester polyurethane. Apolyether urethane having good physical properties can be prepared bymelt polymerization of a hydroxyl-terminated polyether or polyesterintermediate and a chain extender with an aliphatic or aromatic (MDI)diisocyanate. The hydroxyl-terminated polyether has alkylene oxiderepeat units containing from 2 to 10 carbon atoms and has a weightaverage molecular weight of at least 1000. The chain extender is asubstantially non-branched glycol having 2 to 20 carbon atoms. Theamount of the chain extender is from 0.5 to less than 2 mole per mole ofhydroxyl terminated polyether. It is preferred that the polyetherpolyurethane is thermoplastic and has a melting point of about 140° C.to 250° C. or greater (e.g., 150° C. to 250° C.) with 180° C. or greaterbeing preferred.

In a first mode, the polyurethane polymer of the invention can be madesimply by combining a di-, tri- or higher functionality aromatic oraliphatic isocyanate compound with a polyol compound that can compriseeither a polyester polyol or a polyether polyol. The reaction betweenthe active hydrogen atoms in the polyol with the isocyanate groups formsthe addition polyurethane polymer material in a straight forwardfashion. The OH:NCO ratio is typically about 1:1 leaving little or nounreacted isocyanate in the finished polymer. In any unreactedisocyanate compound, reactivity can be scavenged using isocyanatereactive compounds. In a second mode, the polyurethane polymer can besynthesized in a stepwise fashion from isocyanate terminated prepolymermaterials. The polyurethane can be made from an isocyanate-terminatedpolyether or polyester. An isocyanate-capped polyol prepolymer can bechain-extended with an aromatic or aliphatic dihydroxy compound. Theterm “isocyanate-terminated polyether or polyurethane” refers generallyto a prepolymer which comprises a polyol that has been reacted with adiisocyanate compound (i.e., a compound containing at least twoisocyanate (—NCO) groups). In preferred form, the prepolymer has afunctionality of 2.0 or greater, an average molecular weight of about250 to 10,000 or 600-5000, and is prepared so as to containsubstantially no unreacted monomeric isocyanate compound. The term“unreacted isocyanate compound” refers to free monomeric aliphatic oraromatic isocyanate-containing compound, i.e., diisocyanate compoundwhich is employed as a starting material in connection with thepreparation of the prepolymer and which remains unreacted in theprepolymer composition.

The term “polyol” as used herein, generally refers to a polymericcompound having more than one hydroxy (—OH) group, preferably analiphatic polymeric (polyether or polyester) compound which isterminated at each end with a hydroxy group. The chain-lengtheningagents are difunctional and/or trifunctional compounds having molecularweights of from 62 to 500 preferably aliphatic diols having from 2 to 14carbon atoms, such as, for example, ethanediol, 1,6-hexanediol,diethylene glycol, dipropylene glycol and, especially, 1,4-butanediol.Also suitable, however, are diesters of terephthalic acid with glycolshaving from 2 to 4 carbon atoms, such as, for example, terephthalic acidbis-ethylene glycol or 1,4-butanediol, hydroxy alkylene ethers ofhydroquinone, such as, for example, 1,4-di(B-hydroxyethyl)-hydroquinone,(cyclo)aliphatic diamines, such as, for example, isophorone-diamine,ethylenediamine, 1,2-, 1,3-propylene-diamine,N-methyl-1,3-propylene-diamine, N,N′-dimethyl-ethylene-diamine, andaromatic diamines, such as, for example, 2,4- and2,6-toluoylene-diamine, 3,5-diethyl-2,4- and/or -2,6-toluoylene-diamine,and primary ortho- di-, tri- and/or tetra-alkyl-substituted4,4′-diaminodiphenyl-methanes. It is also possible to use mixtures ofthe above-mentioned chain-lengthening agents. Preferred polyols arepolyesters, polyethers, polycarbonates or a mixture thereof. A widevariety of polyol compounds is available for use in the preparation ofthe prepolymer. In preferred embodiments, the polyol may comprise apolymeric diol including, for example, polyether diols and polyesterdiols and mixtures or copolymers thereof. Preferred polymeric diols arepolyether diols, with polyalkylene ether diols being more preferred.Exemplary polyalkylene polyether diols include, for example,polyethylene ether glycol, polypropylene ether glycol,polytetramethylene ether glycol (PTMEG) and polyhexamethylene etherglycol and mixtures or copolymers thereof. Preferred among thesepolyalkylene ether diols is PTMEG. Preferred among the polyester diolsare, for example, polybutylene adipate glycol and polyethylene adipateglycol and mixtures or copolymers thereof. Other polyether polyols maybe prepared by reacting one or more alkylene oxides having from 2 to 4carbon atoms in the alkylene radical with a starter molecule containingtwo active hydrogen atoms bonded therein. The following may be mentionedas examples of alkylene oxides: ethylene oxide, 1,2-propylene oxide,epichlorohydrin and 1,2- and 2,3-butylene oxide. Preference is given tothe use of ethylene oxide, propylene oxide and mixtures of 1,2-propyleneoxide and ethylene oxide. The alkylene oxides may be used individually,alternately in succession, or in the form of mixtures. Starter moleculesinclude, for example: water, amino alcohols, such asN-alkyldiethanolamines, for example N-methyl-diethanolamine, and diols,such as ethylene glycol, 1,3-propylene glycol, 1,4-butanediol and1,6-hexanediol. It is also possible to use mixtures of startermolecules. Suitable polyether polyols are also thehydroxyl-group-containing polymerization products of tetrahydrofuran.Suitable polyester polyols may be prepared, for example, fromdicarboxylic acids having from 2 to 12 carbon atoms, preferably from 4to 6 carbon atoms, and polyhydric alcohols. Suitable dicarboxylic acidsinclude, for example: aliphatic dicarboxylic acids, such as succinicacid, glutaric acid, adipic acid, suberic acid, azelaic acid and sebacicacid, and aromatic dicarboxylic acids, such as phthalic acid,isophthalic acid and terephthalic acid. The dicarboxylic acids may beused individually or in the form of mixtures, for example in the form ofa succinic, glutaric and adipic acid mixture. It may be advantageous forthe preparation of the polyester polyols to use, instead of thedicarboxylic acids, the corresponding dicarboxylic acid derivatives,such as carboxylic acid diesters having from 1 to 4 carbon atoms in thealcohol radical, carboxylic acid anhydrides or carboxylic acidchlorides. Examples of polyhydric alcohols are glycols having from 2 to10, preferably from 2 to 6, carbon atoms, such as ethylene glycol,diethylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol,1,10-decanediol, 2,2-dimethyl-1,3-propanediol, 1,3-propanediol anddipropylene glycol. According to the desired properties, the polyhydricalcohols may be used alone or, optionally, in admixture with oneanother. Also suitable are esters of carbonic acid with the mentioneddiols, especially those having from 4 to 6 carbon atoms, such as1,4-butanediol and/or 1,6-hexanediol, condensation products of(omega-hydroxycarboxylic acids, for example (omega-hydroxycaproic acid,and preferably polymerization products of lactones, for exampleoptionally substituted (ε-caprolactones. These are preferably used aspolyester polyols ethanediol polyadipate, 1,4-butanediol polyadipate,ethanediol-1,4-butanediol polyadipate, 1,6-hexanediol neopentyl glycolpolyadipate, 1,6-hexanediol-1,4-butanediol polyadipate andpolycaprolactones. The polyester polyols have molecular weights of from600 to 5000.

The number of average molecular weight of the polyols from which thepolymer or prepolymers may be derived may range from about 800 to about3500 and all combinations and subcombinations of ranges therein. Morepreferably, the number of average molecular weights of the polyol mayrange from about 1500 to about 2500, with number average molecularweights of about 2000 being even more preferred.

The polyol in the prepolymers can be capped with an isocyanate compoundor can be fully reacted to the thermoplastic polyurethane (TPU). A widevariety of diisocyanate compounds is available for use in thepreparation of the prepolymers of the present invention. Generallyspeaking, the diisocyanate compound may be aromatic or aliphatic, witharomatic diisocyanate compounds being preferred. Included among thesuitable organic diisocyanates are, for example, aliphatic,cycloaliphatic, araliphatic, heterocyclic and aromatic diisocyanates.Examples of suitable aromatic diisocyanate compounds includediphenylmethane diisocyanate, xylene diisocyanate, toluene diisocyanate,phenylene diisocyanate, and naphthalene diisocyanate and mixturesthereof. Examples of suitable aliphatic diisocyanate compounds includedicyclohexylmethane diisocyanate and hexamethylene diisocyanate andmixtures thereof. Preferred among the diisocyanate compounds is MDI due,at least in part, to its general commercial availability and high degreeof safety, as well as its generally desirable reactivity with chainextenders (discussed more fully hereinafter). Other diisocyanatecompounds, in addition to those exemplified above, would be readilyapparent to one of ordinary skill in the art, once armed with thepresent disclosure. The following may be mentioned as specific examples:aliphatic diisocyanates, such as hexamethylene diisocyanate,cycloaliphatic diisocyanates, such as isophorone diisocyanate,1,4-cyclohexane diisocyanate, 1-methyl-2,4- and -2,6-cyclohexanediisocyanate and the corresponding isomeric mixtures, 4,4′-, 2,4′- and2,2′-dicyclohexylmethane diisocyanate and the corresponding isomericmixtures, and, preferably, aromatic diisocyanates, such as2,4-toluoylene diisocyanate, mixtures of 2,4- and 2,6-toluoylenediisocyanate, 4,4′-, 2,4′- and 2,2′-diphenylmethane diisocyanate,mixtures of 2,4′- and 4,4′-diphenylmethane diisocyanate,urethane-modified liquid 4,4′- and/or 2,4′-diphenylmethanediisocyanates, 4,4′-diisocyanatodiphenylethane-(1,2) and 1,5-naphthylenediisocyanate. Preference is given to the use of 1,6-hexamethylenediisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate,diphenylmethane diisocyanate isomeric mixtures having a4,4′-diphenylmethane diisocyanate content of greater than 96 wt. %, andespecially 4,4′-diphenylmethane diisocyanate and 1,5-naphthylenediisocyanate.

For the preparation of the TPUs, the chain-extension components arereacted, optionally in the presence of catalysts, auxiliary substancesand/or additives, in such amounts that the equivalence ratio of NCOgroups to the sum of all the NCO-reactive groups, especially of the OHgroups of the low molecular weight diols/triols and polyols, is from0.9:1.0 to 1.2:1.0, preferably from 0.95:1.0 to 1.10:1.0. Suitablecatalysts, which in particular accelerate the reaction between the NCOgroups of the diisocyanates and the hydroxyl groups of the diolcomponents, are the conventional tertiary amines known in the prior art,such as, for example, triethylamine, dimethylcyclohexylamine,N-methylmorpholine, N,N′-dimethyl-piperazine,2-(dimethylaminoethoxy)-ethanol, diazabicyclo-(2,2,2)-octane and thelike, as well as, especially, organometallic compounds such as titanicacid esters, iron compounds, tin compounds, for example tin diacetate,tin dioctate, tin dilaurate or the tindialkyl salts of aliphaticcarboxylic acids, such as dibutyltin diacetate, dibutyltin dilaurate orthe like. The catalysts are usually used in amounts of from 0.0005 to0.1 part per 100 parts of polyhydroxy compound. In addition tocatalysts, auxiliary substances and/or additives may also beincorporated into the chain-extension components. Examples which may bementioned are lubricants, antiblocking agents, inhibitors, stabilizersagainst hydrolysis, light, heat and discoloration, flameproofing agents,colorings, pigments, inorganic and/or organic fillers and reinforcingagents. Reinforcing agents are especially fibrous reinforcing materialssuch as, for example, inorganic fibers, which are prepared according tothe prior art and may also be provided with a size.

Further additional components that may be incorporated into the PU arethermoplastics, for example polycarbonates andacrylonitrile-butadiene-styrene terpolymers, especially ABS. Otherelastomers, such as, for example, rubber, ethylene-vinyl acetatepolymers, styrene-butadiene copolymers and other PUs, may likewise beused. Also suitable for incorporation are commercially availableplasticisers such as, for example, phosphates, phthalates, adipates,sebacates. The PUs according to the invention are produced continuously.Either the known band process or the extruder process may be used. Thecomponents may be metered simultaneously, i.e. one shot, or insuccession, i.e. by a prepolymer process. In that case, the prepolymermay be introduced either batchwise or continuously in the first part ofthe extruder, or it may be prepared in a separate prepolymer apparatusarranged upstream. The extruder process is preferably used, optionallyin conjunction with a prepolymer reactor.

Fiber can be made by conventional methods and can be made by meltspinning the polyurethane PU or a mixed polyether urethane and theadditive. Melt spinning is a well known process in which a polymer ismelted by extrusion, passed through a spinning nozzle into air,solidified by cooling, and collected by winding the fibers on acollection device. Typically the fibers are melt-spun at a polymertemperature of about 150° C. to about 300° C.

Superabsorbent and other polymeric finer materials have been fabricatedin non-woven and woven fabrics, fibers and microfibers. The polymericmaterial provides the physical properties required for productstability. These materials should not change significantly in dimension,suffer reduced molecular weight, become less flexible or subject tostress cracking, or physically deteriorate in the presence of sunlight,humidity, high temperatures or other negative environmental effects whenused in manufacture. The invention relates to an improved polymericmaterial that can maintain physical properties in the face of incidentelectromagnetic radiation such as environmental light, heat, humidityand other physical challenges.

We have also found a substantial advantage to forming polymericcompositions comprising two or more polymeric materials in polymeradmixture, alloy format, or in a crosslinked chemically bondedstructure. We believe such polymer compositions improve physicalproperties by changing polymer attributes such as improving polymerchain flexibility or chain mobility, increasing overall molecular weightand providing reinforcement through the formation of networks ofpolymeric materials.

In one embodiment of this concept, two related or unrelated polymermaterials can be blended for beneficial properties. For example, a highmolecular weight polyvinylchloride can be blended with a low molecularweight polyvinylchloride. Similarly, a high molecular weight nylonmaterial can be blended with a low molecular weight nylon material.Further, differing species of a general polymeric genus can be blended.For example, a high molecular weight styrene material can be blendedwith a low molecular weight, high impact polystyrene. A nylon-6 materialcan be blended with a nylon copolymer such as a nylon-6,6-6,6,10copolymer. Further, a polyvinylalcohol having a low degree of hydrolysissuch as an 80-87% hydrolyzed polyvinylalcohol can be blended with afully or superhydrolyzed polyvinylalcohol having a degree of hydrolysisbetween 98 and 99.9% and higher. All of these materials in admixture canbe crosslinked using appropriate crosslinking mechanisms. Nylons can becrosslinked using crosslinking agents that are reactive with thenitrogen atom in the amide linkage. Polyvinylalcohol materials can becrosslinked using hydroxyl reactive materials such as monoaldehydes,such as formaldehyde, ureas, melamine-formaldehyde resin and itsanalogues, boric acids and other inorganic compounds. dialdehydes,diacids, urethanes, epoxies and other known crosslinking agents.Crosslinking technology is a well known and understood phenomenon inwhich a crosslinking reagent reacts and forms covalent bonds betweenpolymer chains to substantially improve molecular weight, chemicalresistance, overall strength and resistance to mechanical degradation.

We have found that additive materials can significantly improve theproperties of the polymer materials in the form of a nanofiber. Theresistance to the effects of heat, humidity, impact, mechanical stressand other negative environmental effect can be substantially improved bythe presence of additive materials. We have found that while processingthe microfiber materials of the invention, the additive materials canimprove the oleophobic character, the hydrophobic character, and canappear to aid in improving the chemical stability of the materials. Webelieve that the nanofibers of the invention in the form of a microfiberare improved by the presence of these oleophobic and hydrophobicadditives as these additives form a protective layer coating, ablativesurface or penetrate the surface to some depth to improve the nature ofthe polymeric material. We believe the important characteristics ofthese materials are the presence of a strongly hydrophobic group thatcan preferably also have oleophobic character. Strongly hydrophobicgroups include fluorocarbon groups, hydrophobic hydrocarbon surfactantsor blocks and substantially hydrocarbon oligomeric compositions. Thesematerials are manufactured in compositions that have a portion of themolecule that tends to be compatible with the polymer material affordingtypically a physical bond or association with the polymer while thestrongly hydrophobic or oleophobic group, as a result of the associationof the additive with the polymer, forms a protective surface layer thatresides on the surface or becomes alloyed with or mixed with the polymersurface layers. For 0.2-micron fiber with 10% additive level, thesurface thickness is calculated to be around 50 Å, if the additive hasmigrated toward the surface. Migration is believed to occur due to theincompatible nature of the oleophobic or hydrophobic groups in the bulkmaterial. A 50 Å thickness appears to be reasonable thickness forprotective coating. For 0.05-micron diameter fiber, 50 Å thicknesscorresponds to 20% mass. For 2 microns thickness fiber, 50 Å thicknesscorresponds to 2% mass.

Preferably the additive materials are used at an amount of about 2 to 25wt. %. Oligomeric additives that can be used in combination with thepolymer materials of the invention include oligomers having a molecularweight of about 500 to about 5000, preferably about 500 to about 3000including fluoro-chemicals, nonionic surfactants and low molecularweight resins or oligomers. Examples of useful phenolic additivematerials include Enzo-BPA, Enzo-BPA/phenol, Enzo-TBP, Enzo-COP andother related phenolics were obtained from Enzymol International Inc.,Columbus, Ohio.

An extremely wide variety of fibrous filter media exist for differentapplications. The durable nanofibers and microfibers described in thisinvention can be added to any of the media. The fibers described in thisinvention can also be used to substitute for fiber components of theseexisting media giving the significant advantage of improved performance(improved efficiency and/or reduced pressure drop) due to their smalldiameter, while exhibiting greater durability.

A media construction according to the present invention can include afirst layer of permeable coarse fibrous media. A first layer ofnanofiber with super absorbent particulate, fiber or fabric and optionalparticulate is secured to the first surface of the first layer ofpermeable coarse fibrous media. The nanofiber and the particulate, fiberor fabric layer can be formed simultaneously or separately. Preferablythe first layer of permeable coarse fibrous material comprises fibershaving an average diameter of at least 10 microns, typically andpreferably about 12 (or 14) to 30 microns. The element of the invention,including the nanofiber and dispersed particulate layer can be combinedwith a variety of other layers as discussed elsewhere in thespecification. The layers can be made as a flat or coplanar sheetversion of the layers of the invention or can be pleated, corrugated orformed into virtually any other cross-sectional shape needed to form thelow pressure drop flow through element of the invention. The substratecan comprise an expanded PTFE layer or Teflon layer. The substrate canalso be substantially free of a Teflon, an expanded PTFE layer. Suchlayers are useful in a variety of in use applications that can provideboth filtration and activity from the active particulate. Such layerscan also aid in confining the particulate into the element.

In preferred arrangements, the first layer of permeable coarse fibrousmaterial comprises a material which, if evaluated separately from aremainder of the construction by the Frazier permeability test, wouldexhibit a permeability of at least 1 meter(s)/min, and typically andpreferably about 2-900 meters/min. Herein when reference is made toefficiency, unless otherwise specified, reference is made to efficiencywhen measured according to ASTM-1215-89, with 0.78μ monodispersepolystyrene spherical particles, at 20 fpm (6.1 meters/min) as describedherein.

A variety of methods can be utilized for the manufacture of nanofiberwith the super absorbent particulate or fiber or other components. Chunget al., U.S. Pat. No. 6,743,273; Kahlbaugh et al., U.S. Pat. No.5,423,892; McLead, U.S. Pat. No. 3,878,014; Barris, U.S. Pat. No.4,650,506; Prentice, U.S. Pat. No. 3,676,242; Lohkamp et al., U.S. Pat.No. 3,841,953; and Butin et al., U.S. Pat. No. 3,849,241; all of whichare incorporated by reference herein, disclose a variety of nanofibertechnologies. The nanofiber of the invention is typically electrospunonto a substrate. The substrate can be a pervious or imperviousmaterial. In filtration applications non-woven filter media can be usedas a substrate. In other applications the fiber can be spun onto animpervious layer and can be removed for down stream processing. In suchan application, the fiber can be spun onto a metal drum or foil. Thesubstrate can comprise an expanded PTFE layer or Teflon® layer. Suchlayers are useful in a variety of applications that can provide bothfiltration and activity from the active particulate.

The electrostatic spinning process can form the microfiber or nanofiberwith super absorbent particulate or fiber. A suitable apparatus forforming the fiber is illustrated in Barris U.S. Pat. No. 4,650,506. Thisapparatus includes a reservoir in which the nanofiber forming polymersolution is contained, a pump and a rotary type emitting device oremitter to which the polymeric solution is pumped. The emitter generallyconsists of a rotating union, a rotating portion including a pluralityof offset holes and a shaft connecting the forward facing portion andthe rotating union. The rotating union provides for introduction of thepolymer solution to the forward facing portion through the hollow shaft.Alternatively, the rotating portion can be immersed into a reservoir ofpolymer fed by reservoir and pump. The rotating portion then obtainspolymer solution from the reservoir and as it rotates in theelectrostatic field, the electrostatic field aligned toward thecollecting media accelerates a droplet of the solution as discussedbelow.

Facing the emitter, but spaced apart therefrom, is a substantiallyplanar grid 60 upon which the collecting media (i.e. substrate orcombined substrate is positioned. Air can be drawn through the grid. Thecollecting media is passed around rollers which are positioned adjacentopposite ends of grid. A high voltage electrostatic potential ismaintained between emitter and grid by means of a suitable electrostaticvoltage source and connections and which connect respectively to thegrid and emitter.

In use, the polymer solution with super absorbent particulate or fibercan be pumped to the rotating union or reservoir from reservoir. Theforward facing portion rotates while liquid exits from holes, or ispicked up from a reservoir, and moves from the outer edge of the emittertoward collecting media positioned on the grid. Specifically, theelectrostatic potential between grid and the emitter imparts a charge tothe material that cause liquid to be emitted there from as thin fiberswhich are drawn toward grid where they arrive and are collected onsubstrate or an efficiency layer. In the case of the polymer insolution, solvent is evaporated from the fibers during their flight tothe grid; therefore, the fibers arrive at the substrate or efficiencylayer without substantial solvent. The nanofibers bond to the substratefibers first encountered at the grid. Electrostatic field strength isselected to ensure that as the polymer material it is accelerated fromthe emitter to the collecting media, the acceleration is sufficient torender the material into a very thin microfiber or nanofiber structure.Increasing or slowing the advance rate of the collecting media candeposit more or less emitted fibers on the forming media, therebyallowing control of the thickness of each layer deposited thereon. Therotating portion can have a variety of beneficial positions. Therotating portion can be placed in a plane of rotation such that theplane is perpendicular to the surface of the collecting media orpositioned at any arbitrary angle. The rotating media can be positionedparallel to or slightly offset from parallel orientation.

A sheet-like substrate is unwound at a station. The sheet-like substrateis then directed to a splicing station wherein multiple lengths of thesubstrate can be spliced for continuous operation. The continuous lengthof sheet-like substrate is directed to a nanofiber technology stationcomprising the spinning technology discussed above, wherein a spinningdevice forms the nanofiber and lays the nanofiber in a filtering layeron the sheet-like substrate. After the nanofiber layer is formed on thesheet-like substrate in the formation zone, the nanofiber layer andsubstrate are directed to a heat treatment station for appropriateprocessing. The sheet-like substrate and nanofiber layer is then testedin an efficiency monitor and nipped if necessary at a nip station. Thesheet-like substrate and fiber layer is then steered to the appropriatewinding station to be wound onto the appropriate spindle for furtherprocessing.

The web, element or filter media of the invention when used in afiltration mode should have a minimal pressure drop for acceptablefunction as a filter and to obtain the activity of the super absorbentparticulate or fiber or optional insert or active particle(s). Suchpressure drop information is known for the types of filtration devicesof the invention. Such pressure drop parameters define the useful lifeof the filtration element of the invention. The element of theinvention, when used in a flow through mode with no intervening filterlayer, should provide little or no resistance to the flow of the mobilefluid through the element (e.g.; less than 0.1 inches or less than 1-5inches of water). Flow should not be constrained but the residence time,however, of the fluid within the element must be sufficient to obtainsufficient contact and absorbance/absorbance/reaction needed in theelement to obtain the desired activity form the active particulatewithin the element. A useful residence time, depending on activeparticulate can be from about 0.01 to as long as it is necessary toobtain some removal of entrained materials. The residence time can be0.02 second to as much as 5 minutes and typically ranges from about 0.01to 60 seconds 0.01 to 1 second or as little as 0.02 to 0.5 second. Thelifetime of such a unit is defined by the load of active particulate andthe residual amount of activity in the unit. Some small amount ofpressure drop can be designed into the element to slow the flow andextend residence time without substantially impeding flow.

There are two distinct mechanisms of capture of super absorbentparticulate or fiber in the nanofiber matrix:

The web can be made by mechanical entanglement of the particles insidethe nanofiber matrix that inhibit the particle or fiber from movingfreely inside the composite. The result is a nanofiber network that actsmuch like a spider web, capturing and holding the particles on itself.As more layers are deposited, the network turns into a nanofibrousmatrix of nanofiber and particles.

Adhesion between the particle or fiber and nanofibers as a direct resultof solution spinning of the nanofibers. Because nanofibers were createdfrom a polymer solution using electrospinning process, as the nanofibersland on the target, they may retain a very small amount of the solventin their structure and hence they have the ability to fuse onto thesuper absorbent particulate or fiber.

Composites with even higher particulate efficiency can be made byseveral means:

Increasing the thickness of the overall composite

Keeping the thickness of the overall composite the same, however, addinghigh efficiency layer made of very fine (around 0.25 micron) nanofiberscoated on the bottom and top of the nanofiber/activated carbon particlecomposite

The second method is preferable, simply because it would allow keepingthe chemi-adsorptive properties of the composite the same, while theparticulate efficiency can be adjusted independently.

The application of this invention is to purify or separate fluidstreams, such streams including liquid streams and gaseous streams. Thefilter element of the invention is placed in a location or environmentsuitable for a particular application, such that a contaminate-ladedfluid stream can pass through or pass by the element, and contaminatescan be removed. Fluid streams for the application include liquid orgaseous streams that can contain contaminates such as dust particulate,water, solvent residue, oil residue, mixed aqueous oil residue, harmfulgases. Mobile liquid streams include fuels, oils, solvent streams, etc.The streams are contacted with the flow-through or flow-by structures ofthe invention to remove liquid or particulate contaminants, colorforming species, and soluble impurities. The contaminates to be removedby application of the invention also include biological products suchas, for example, prions, viruses, bacteria, spores, nucleic acids, otherpotentially harmful biological products or hazardous materials.

In one aspect, the filter element of the invention can be placed in avent for an enclosure, such that the interior of the enclosure ismaintained at substantially reduced moisture content with respect to theexterior of the enclosure, because the adsorbent media removes moisturefrom the interior of the enclosure. The enclosure in which the filterelement is placed includes an enclosure containing an electronic circuitor device, wherein the electronic circuit or device includes, withoutlimitation, an organic light emitting diode, a hard drive, a display, orsome combination thereof. For example, the filter element of theinvention can be used as a moisture-absorbing flexible display for anelectronic device. The flexible display comprises a lighted display(including displays formed using light emitting diodes) combined withthe filter element, which absorbs moisture from the environment orenclosure in which the flexible display is used. Other uses include inseals for bearings or hydraulic cylinders to protect from any ingress ofwater, fuel pumps filters to remove water when fueling vehicle, wet-drycapture for vacuums, sweepers, and scrubbers, crank-case ventilation toprevent plugging from condensed liquid, drying bulk oil and fuel storagetanks, inlet air filtration in gas turbine systems to prevent saltmigration (in environments subjected to humid, salt-laden air), toprotect electronic enclosures in equipment and aqueous-hydrocarbonseparations for waste reduction.

Depending on the amount of performance necessary, this media could beused in various applications and in various forms including particlefiltration and chemical filtration in the same layer or confined space,combination particle filter and chemical filter for use in a gas turbineapplication, chemical filter as the only option for gas turbine systems,high flow applications in the semiconductor industry for fan assemblies,point of use, and full filter fabrication locations or labs,applications that require a “gettering” type filter, point of usefiltration for semiconductor within clean rooms with minimal space andmaximum efficiency, tool mount filter for semiconductor applicationswithin clean rooms with minimal space and maximum efficiency, high flowapplications in ceiling grids for clean rooms applications, applicationsthat require a reduced weight but similar efficiencies, applicationsthat require a reduced pressure drop but similar efficiencies, locationsrequiring low particle shedding, or layers of chemical filters can beused. Respirators, dust masks, surgical masks and gowns, surgicaldrapes, HEPA replacement including filters for semiconductor processingequipment and clean rooms, sir filtration for gasoline, natural gas ordiesel powered engine, inlet filtration for air compressors, inletfiltration for dust collection equipment, vacuum cleaner filters, acidgas removal from air, cartridges for dryers, CBRN protection materials,wound care, HVAC applications, cabin air filtration, room air cleaner,fuel filter, lube filter, oil filters, liquid filters, air filter forfuel cell application, process filters, insulation material, filters fordisk drives, filters for electronics enclosures, chromatographicseparations, bio-separations can all be made with the materials of theapplication. The materials of the invention can be used as a waterseparation structure that acts as a reservoir for water impurity.

The fiber structures of the invention can be used as flat or rolledmedia. By rolling or alternately stacking flat sheet chemical filtrationwith a spacing media, this can create flow channels within the element.These channels allow the gas fluid to be filtered to pass across themedia in such a manner as to perform the desired reactions, while, atthe same time, maintaining a lower pressure drop than the chemicalfiltration media would allow by itself. The spacing media may bechemically treated to assist in filtration or may be inert. Such flowchannels in a filter element can be created by co-rolling the spacingmedia and chemical filtration media around a chemically active or inertcore. Once the nanofiber layer containing super absorbent particulate orfiber, the active or active inert particulate of the invention isprepared, the layer must be mechanically assembled into a useful activeor adsorbent or absorbent structure. Nanofiber layers are typically spunonto a substrate material which can be a scrim, a cellulosic substrate,a mixed synthetic cellulosic substrate or a purely cellulosic substrate.The nanofiber layers containing the super absorbent particulate or fiberor active or inert particulate are electrospun onto said substrates andthe substrate can then be rolled into an absorbent structure.Alternatively, the layer can be cut into similar portions and stacked toform an absorbent layer. The internal structure of any assembly of thenanofiber layers has sufficient air flow to ensure that the air can passeasily through the assembly. In this case, the assembly would act, notas a filter, but purely as an absorbent assembly structure. In analternative structure, the layers of nanofiber and reactive or activeparticulate can be assembled into a structure that filters and reacts,adsorbs, or absorbs. Such varying structures have applications in avariety of end uses. The former structure has little or no filtrationproperties and can remove reactive contaminant materials from fluidstreams such as air streams or liquid streams simply using aflow-through mechanism. The latter structure can remove particulate, andcan remove chemical species from a fluid such as air, simultaneouslywith the filtration operations.

In certain preferred arrangements of the wound or stacked layers of theinvention, the media can be configured for a straight through floweither in a flow without filtration properties or a flow includingpassage through a filter layer. In such a fluid flow, the fluid willenter in one direction through a first flow face and exit moving in thesame direction from a second flow face. Within the filter structure, thefluid may not interact with a surface that acts as a filter or it mayinteract with a flow, may contact a surface that obtains filtrationproperties. Generally, one preferred filter construction is a woundconstruction including a layer of media that is turned repeatedly abouta center point forming a coil such that the filter media will be rolled,wound or coiled. One preferred useful structure is a corrugatedstructure in which the material has a fluted construction. Such flutescan be formed and combined with a face sheet. Once the corrugated mediais combined with the uncorrugated media in the form of a face sheet, theresulting structure can be coiled and formed into a useful assembly.When using this type of media construction, the flutes form alternatingpeaks and troughs in the corrugated structure. In certain constructions,the upper flutes form flute chambers which can be closed at a downstreamand while the flute chambers have upstream ends that are closed to formother rows of flutes. In such a structure, the opened and closed areascause the fluid to pass through at least one corrugated wall to obtainfiltration properties from the corrugated layer. In use, such corrugatedmedia in a coiled assembly provides an intake area for a fluid streamsuch as air. Air enters a flute chamber in an open upstream end, theunfiltered fluid flow is not permitted to pass through a closed downstream end but is forced to proceed through a corrugated layer or flutedsheet to contact either the fiber of the corrugated layer or the activeparticulate to either filter particulate from the fluid stream, or toensure that the material dispersed or dissolved in the fluid stream isreacted with, absorbed, or adsorbed onto the active particulate.

As discussed above, the nanofiber containing the super absorbentparticulate or fiber or super absorbent fiber with optional particulatecan be used to treat a mobile fluid phase such as a gas or liquid. Thegas or liquid can be treated by the webs of the invention to interactwith components of the mobile fluid phase. Components of the mobilefluid phase can be adsorbed or chemically reacted by the particulate inthe web. Alternatively, the particulate in the web can be used to addback materials into the fluid stream in a reverse addition or controlleddesorption mode. In such a mode, the particulate can be pretreated witha material such that in a flow by or flow through mode, the material inthe particulate can be released or selectively desorbed into the mobilefluid.

Disc drive technology is demanding and requires maintaining operatingparameters of temperature, pressure that leads to long operating life ofthe disk drive structure. Maintaining such an environment requires thefilter structures that can be useful to exclude particulate from thedescribed environment. Such filter designs are optimal with the pressuredrop of the breather or filter structures low. Preferred disk drivefilter breather filter structures can preferably include properties thatresult in little or no introduction of moisture into the disk driveenvironment or space within the disk drive housing. An optimum filterstructure can permit the removal of moisture from the interior of thedisk drive while permitting no entry of moisture as the disk drivestructure cycles during heating and cooling obtaining in the operationof the disk drive. The disk drive breather or filter structure of theinvention can optimize porous size and structure poor distribution,rigidity or flexibility of the breather filter material and appropriatesurface energy to aid in moisture absorption from the ambient air.

In one mode, the breather filter structure of the invention can work asa one way moisture transfer device. In such a mode, the breather filterstructure can absorb moisture from the ambient air as the air enters thedisk drive housing during normal operation conditions. However, thetechnology of the invention can also be used as a structure that at aminimum can absorb moisture as the ambient air is directed from thehousing and as the ambient air is directed into the housing. Thestructure of FIG. 5 is one embodiment of a structure of the inventionusing two layers of filter materials that can contain either superabsorbent particulate or fiber in the web or media of the invention.

The structures of the invention can also be used in separating entrainedgases of a minor proportion in a gas stream. Such gas from gasseparation can involve a structure of the invention wherein superabsorbent fiber or super absorbent particulate can be used in a web forsuch separations. Very commonly intake air from a variety of industrialapplications require that the intake air be dry, free of contaminants,such as dust, oil, urban aerosol pollution or other contaminants. Suchcontaminants can often interfere with the working mechanisms of thestructure or can result in contamination of a product or product screen.One embodiment of technology of the invention can involve a reducedparticle size particulate or reduced fiber diameter particle or fiber ofthe super absorbent material to improve absorption, a surfacephenomenon. Such smaller fiber or particulate can improve the voidvolume of the packing, while at the same time, obtaining an interstitialvelocity through the material lower than conventional designs to improveabsorption efficiency. This improves efficiency of the material andpressure drop.

One particularly important application of this technology is the use ofthe technology in compressed air production. Compressed air isindispensable process medium for many industrial commercialapplications. Clean, useful compressed air must be dry, free of oilparticulate and other contaminates to avoid damage to the compressed airand to the usefulness of the resulting products made using thetechnology. Currently, absorbents used in compressed air involve veryhigh pressure drops in normal operation a long time for regeneration andcan cause introduction of harmful particles into the process equipment.A preferred compressed air dryer structures can include a superabsorbent particle or a super absorbent fiber in a nanofiber matrix withoptional absorbents/adsorbents or reactive structures. In theseapplications, the optional particulate can include zeolites, absorbentsalts, such as lithium chloride and other materials. Alternatively, thedryer structures of the invention used in compressor applications can bemade of a nanofiber layer containing a superabsorbent fiber within thenanofiber web or as a separate web or layer in the overall dryerstructure.

In many technologies, water can be a contaminate in a variety of usefulfluids. Typically, fluids in which water is substantially not soluble oromissible can accumulate a large proportion of contaminating water. Somewater is dissolved or dispersed into the phase of the fluid; however, alarge amount of water can also collect as a separate phase in contactwith the fluids. In a number of industrial applications, the presence ofwater can be a problem including jet fuel, E85 fuel, and gasohol. Thetechnology of the invention can be used to separate water fromhydrocarbon liquid such as fuels, oils, and other materials prior tointroduction of the material into a storage tank or vehicle tank. Insuch an application, the hydrocarbon stream is passed through astructure of the invention wherein the super absorbent fiber orparticulate absorbs water from the hydrocarbon stream resulting in aclean, improved fuel. Also, in oil and fuel reservoirs, the structuresof the invention can be used to remove contaminated water from storagefacilities. Using such technologies, contaminating water can be kept ata concentration well below saturation point in the fuel or oil layer.Additionally, the separation of water from E85 or gasohol or other suchethanol containing fuels can also be obtained. Such a structure can beused as a continuous filter where in the contents of a reservoir iscontinuous passed through the filter thus removing water from thecontents of the reservoir in a continuous operations mode.Alternatively, the structures of the invention can be inserted into thereservoirs at a low point in the tank where aqueous materials separatingfrom the hydrocarbon liquid collect which can be absorbed by a removedfrom the tank. Alternately, when the hydrocarbon material is removedfrom the tank, the material can be passed through a high capacitystructure of the invention to remove fuel when removed.

Aviation Fuse Filters can be regarded as the last resort at capturingwater from getting into the fuel tank of an aircraft. These filters aredesigned to swell in the presence of water leading to a sharp increasein pressure drop, to which the fueling personnel responds by shuttingoff the flow. The swelling of the fuse filter takes place due to thepresence of super absorbent polymer (SAP) particle or fiber dispersedbetween layers of synthetic scrims or tissue in general. SAP particle orfiber can absorb water very fast typically at very high masses comparedto their original mass. They can hold the water for long periods of timeand do not bleed the water out.

There are several important issues, which are equally important that onewants to avoid when dealing with these types of aviation fuse filtersand fueling. One of such issues is the presence of water downstream fromthe fuse filter, which would eventually end up in the fuel tank of theaircraft. The water in the fuel tank and lines is absolutely unwantedsince it can freeze up in the lines at high altitudes and sub-zerotemperatures leading to a potential failure of the aircraft engine. Theother key issue is migration of the SAP particles downstream into thefuel tank, which also is unwanted as they can lead up to the fouling ofthe jet engines.

There are several reasons why water and super absorbent particulate orfiber could penetrate downstream of the fuse filter and inside the fueltank of the aircraft. One is more of an intrinsic property of the mediaas it can not swell-shut fast enough or not shut-off completely that inthe presence of large enough quantities of water, the water penetratesdownstream. In the case of super absorbent particulate or fibermigration downstream, the absolute glass media in the far downstream ofthe composite media, the glass is intended to capture any particle thatbecomes mobile enough to flow with the fuel. There are certain reasonswhy they can become mobile and migrate downstream: particles aretypically not bound tightly inside the tissue or synthetic sheets; andthat electrostatic discharges due to the flow of highly insulative jetfuel and composite media that has prone to triboelectric charging can begenerated resulting in holes throughout the depth of the media whichacts like leak paths for the SAP particles. Three existing commerciallyavailable aviation fuse filters were evaluated and used as benchmarksagainst the inventive designs created during the program. These threedifferent elements were purchased commercially from three differentsuppliers.

An improved composite media for uses in aviation fuel monitoring servingas a fuse during fueling of aircraft is shown. It is designed to addresstwo of the most critical aspects, which are presence of unwanted waterand SAP particles inside the fuel tank of an aircraft that leads to thefouling of the fuse filters, discontinuation of the fueling andpotential hazards associated by the presence of water and SAP particleinside the aircraft fuel tank. The structures of the invention can beused to minimize or eliminate the penetration of water downstream of thefuse filter, and minimize or eliminate the migration of SAP particlesdownstream of the fuse filter

The structures of the invention can be used to obtain a quick shut-offof the fuse filter in the presence of water inside the fuel. Thepresence of water is indicated by a sharp increase in pressure dropacross the filter. The structures of the convention can obtain controlof SAP particle migration such as by eliminating the one-dimensionalmorphology of the particles that makes them more susceptible tomigration by employing two-dimensional fibrous super absorbent fibers

In order to accomplish these goals with in the framework of theadvancements described above, both external and internal mediapossibilities are useful. Three of such aspects proved very suited forthe application based on the experimental results which will bepresented in the following sections. Super absorbent fibrous nonwovenmedia can be used. This particular super absorbent media is a relativelythick nonwoven composed of super absorbent particulate or fibers thatare laid down in a lofty and open network leading up to desirable lowpressure drop (high permeability). Dry material properties were assessedand compared using air permeability measurements. This particular superabsorbent media came in with cellulose backing laminated to it by thesupplier. During tests in-house the backing was removed by simplyseparating it from the super absorbent media. Nanofiber treatment of asuper absorbent fibrous nonwoven media can be used. The nanofibertreated super absorbent nonwoven composite is based on the use of SAPparticulate or a coating of the super absorbent material on a nonwovenmedia surface with a homogenous nanofiber network. The fibers aredesigned to be hydrophilic and elastic, which makes the composite wetevenly in the presence of water due the hydrophilic nature of thefibers. The fibers help transport water through capillary means and theelasticity of the fibers ensures that any small fragments of the superabsorbent nonwoven even when wet, are tightly bounded even in thepresence of water as the water causes the swelling of super absorbentfibers, which results in a significant increase in volume. Through theirelastic properties, the fibers can manage the expansion of the superabsorbent substrate fibers and the structure is held together as a solidcomposite, without super absorbent fiber migration out of the composite.In this configuration, nanofiber can be applied to the downstream of thesuper absorbent nonwoven media in order to facilitate the capturing ofthe wet super absorbent fibers. In other words, when this nanofibernetwork is applied to the upstream of the super absorbent nonwoven, itimpacts the wetting character of the media, and when the nanofibernetwork is on the downstream side of the nonwoven, they facilitate thecapture of any fugitive small fragments from the super absorbentnonwoven. In one or both modes of operation, the nanofiber provide anadvantage over the untreated super absorbent nonwoven media.

In either mode of operation, the nanofiber can be applied onto othertypes of substrates i.e. scrims, glass etc. to serve the same desiredfunctions. As long as these nanofiber are present either on the upstreamand/or on the downstream side of the super absorbent nonwoven substrate,they will serve their purpose of aiding wetting on the upstream andcapturing fugitive SAP fragments on the downstream of the superabsorbent nonwoven media.

The nanofiber was generated by electrospinning fibers from thermoplasticpolyurethane (grade SP-80A-150) obtained from Noveon, Inc. Nanofibersare laid on to the super absorbent substrate in a random network with arange of different fiber sizes visible. See, FIG. 3. As it is describedthrough the use of examples, the invention makes use of the superabsorbent nonwoven media and the nanofiber coated on one or both sidesof the nonwoven by layering of their combinations and in combinationwith other layers such as coalescing media and glass media.

A nanofiber composite can be used. This composite is based on SAPparticles or fiber dispersed inside a nanofiber network in a homogenousmanner, where each particle or fiber is arrested by the presence of manyfibers surrounding it. The fibers are designed to be hydrophilic andelastic, which makes the composite wet evenly in the presence of waterdue the hydrophilic nature of the fibers. The fibers help transportwater through capillary means and the elasticity of the fibers ensuresthat the particles re tightly bounded even in the presence of water asthe water causes the swelling of SAP particles and tremendous increasein volume. Through their elastic properties, the fibers can manage theexpansion of particles and the structure is held together as a solidcomposite, without particle migration out of the composite.

The nanofiber/SAP composite was generated by electrospinning fiber ofthermoplastic polyurethane (grade SP-80A-150) obtained from Noveon, Inc.and incorporating SAP particles obtained from BASF, the trade name ofthe SAP particles were Luquasorb®-1010. For reference purposes aScanning Electron Micrograph of the composite is presented in FIG. 2below, where SAP particles can be seen within a network of nanofibers.Also visible in FIG. 2 is part of the 5 um Synteq XP glass media used asa substrate to facilitate the support function for nanofiber/SAPcomposite.

As it will be described in the following section through the use ofexamples, the invention makes use of these two highly water absorptivemedia by either themselves or by layering of their combinations and incombination with other layers such as coalescing media and glass media.It should be understood that this invention can also be used for otherliquid or gas streams where a “fuse” is useful to shut off flow ifexcessive water is present. This could include other hydrocarbon fluids,other nonpolar or polar fluids, gas streams including air, natural gas,process gasses, etc at any operating pressure. Following tables depictsome of the composite media that was assembled with the use of eitherthe super absorbent fibrous nonwoven media alone or with the coatings ofthe nanofiber network on it or the nanofiber/super absorbent particulateor fiber or a combination of the two as seen in Examples 5 and 6. In allof these media, 5 um Synteq was used as the last layer (closest to thedownstream) of the composite as an absolute filter to avoid themigration of SAP particles downstream, and a Reemay scrim was used asthe top layer (closest to the upstream) as a protective sheet. In someof these examples, we have used a meltblown layer for water coalescingas well (examples 1, 3, 5, 6, 7 and 8). In some cases, the number ofwraps of certain layers was changed as well, and they're noted on thetables below. For example, the difference between Examples 1 and 3 isthe presence of an additional wrap of superabsorbent fibrous nonwovenmedia on Example 3.

In some of the examples presented here, a gradient 2 layer Bicomponent(Synteq XP) media was used to remove large particles. Also, in some ofthe composition, a meltblown media with 3 gradient layer structure wasused for water coalescing.

Group 1 Example 1 # Wraps Media Description ~ Reemay Scrim Upstream 1Gradient 2 layer Synteq XP 1 Meltblown layer ↓ 1 Superabsorbent nonwoven2 5 um Synteq XP Downstream Example 2 # Wraps Media Description ~ ReemayScrim Upstream 1 Gradient 2 layer Synteq XP ↓ 1 Superabsorbent nonwoven2 5 um Synteq XP Downstream

Group 2 Example 3 # Wraps Media Description ~ Reemay Scrim Upstream 1Gradient 2 layer Synteq XP 1 Meltblown layer ↓ 2 Superabsorbent nonwoven2 5 um Synteq XP Downstream Example 4 # Wraps Media Description ~ ReemayScrim Upstream 1 Gradient 2 layer Synteq XP ↓ 2 Superabsorbent nonwoven2 5 um Synteq XP Downstream Example 5 # Wraps Media Description ~ ReemayScrim Upstream 1 Gradient 2 layer Synteq XP 1 Meltblown layer 1Nanofiber super absorbent ↓ particulate or fiber coating onSuperabsorbent nonwoven 1 5 um Synteq XP Downstream Example 6 # WrapsMedia Description ~ Reemay Scrim Upstream 1 Gradient 2 layer Synteq XP 1Meltblown layer 1 Superabsorbent nonwoven ↓ 1 5 um Synteq XP andNanofiber/ super absorbent particulate or fiber coating on 5 um SynteqXP} Downstream

Group 3 Example 7 # Wraps Media Description ~ Reemay Scrim Upstream 1Gradient 2 layer Synteq XP 1 Meltblown layer 2 Hydrophilic nanofibercoated Superabsorbent nonwoven and ↓ flipped which leads to (Nanofiber/SA fiber/SA fiber/Nanofiber layering) 2 5 um Synteq XP DownstreamExample 8 # Wraps Media Description ~ Reemay Scrim Upstream 1 Gradient 2layer Synteq XP 1 Meltblown layer ↓ 2 Superabsorbent nonwoven 2 5 umSynteq XP Downstream

Group 4 Example 9 # Wraps Media Description ~ Reemay Scrim Upstream 1Gradient 2 layer Synteq XP ↓ 2 Meltblown layer 2 5 um Synteq XPDownstream Example 10 # Wraps Media Description ~ Reemay Scrim Upstream1 Gradient 2 layer Synteq XP 2 Meltblown layer ↓ 2 5 um Synteq XP withnanofiber coating Downstream Example 11 # Wraps Media Description ~Reemay Scrim Upstream 1 Gradient 2 layer Synteq XP 2 Meltblown layer ↓ 45 um Synteq XP with nanofiber coating DownstreamThe preferred Jet-A filter construction is layered as follows:

Group 5 Example 12 # Wraps Name Description Scrim Lightweight spunbondpolyester Upstream 1 Synteq XP Synthetic Depth Loading Liquid Media(basis weight 80 g/m², 0.35 mm thickness, approx. 30 μm filter rating) 1Synteq XP Synthetic Depth Loading Liquid Media (basis weight 60 g/m²,0.30 mm thickness, approx. 20 μm filter rating) 1 Meltblown 3 LayerGradient Composite Polyester Meltblown (basis weight 140 g/m², 0.55 mmthickness, approx. 10 μm filter rating) 1 Nanofiber Electrospunpolyurethane Nanofibers on Reemay ↓ #2014 scrim (LEFS Efficiency 99% @0.3 um 10.5 ft/min) 1 SAP Concert Indistries DT325.100 airlaid gradew/type 101 superabsorbent fibers from Technical Absorbents 1 NanofiberElectrospun polyurethane Nanofibers on Reemay #2014 scrim (LEFSEfficiency 99% @ 0.3 um 10.5 ft/min) 2 Synteq XP Synthetic Depth LoadingLiquid Media (basis Downstream weight 40 g/m², 0.25 mm thickness,approx. 5 μm filter rating)A Jet A1 Fuel Fuse Prototype was used in a Testing Protocol Using Dieselas Model Fuel. Elements were 5 inches long and ran at the same flux rateas the full scale elements are specified to be run at. Also, instead ofthe Jet A1 fuel, we have used diesel fuel as the model fuel. Based onthe Interfacial Tension (IFT) and MSEP measurements of diesel and Jet A1fuels, it is apparent that the emulsified water is harder to separatefrom diesel rather than Jet A1 since Jet A1 fuel has higher IFT and MSEPratings than diesel fuel. And it is known in the emulsified water fuelseparation field that higher IFT and MSEP leads to better separationefficiency. We have reported all the important properties of both thediesel (depending upon where it was purchased from, the properties vary)and the Jet A1 fuel. These properties were: density, surface tension,IFT and MSEP. In occasions where the diesel fuel properties variedsignificantly from one supplier to the other, we have included one ofthe baseline elements in the testing as a control test sample.

The Free Water Pressure Drop Test was used. Using new element saturateddiesel fuel was pumped at 5 gpm. Water was introduced into the pumpinlet at a rate to put 100 ppm free water by volume into the diesel.Feeding of 100 ppm water and diesel to the filter was continued untilthe pressure drop reached 50 psi. During the test, this procedure wasfollowed and data collected which included recording of the pressuredrop and temperature at start and approximately every 2 minutes,collecting effluent sample for diesel water content test until 50 psidwas reached.

The Water Slug Test (test unit shown in FIG. 1) used in the testing usesa test system. The system was filled with water saturated diesel andcirculated at 5 gpm. A water slug equal to the water absorbing capacityof the filter plus enough to fill the inlet plumbing and the filterhousing (2 liters) was introduced at 5 gpm. The time it takes to reach50 psi differential pressure was recorded and effluent sample fordiesel/water ratio analysis was taken and measurements were conducted.

Typical performance of the preferred design in Example 12 internaltesting 100 ppm water addition test is shown in FIG. 7. Additionaltesting of DCI elements was conducted at South West Research institutewith Jet A fuel and 50 ppm free water per the IP Draft Standard 15835^(th) edition Qualification test 4.5.2. The data of FIG. 8 alsodemonstrates the quicker shutoff performance of the preferred DCI designin comparison to other competitor and DCI designs.

We also conducted testing for SAP migration. An element 5.75 inches longwith layers outside to in of depth loading media, coalescer media, 2layers of superabsorbent nonwoven and a double wrap of 5 um Synteq XPwere constructed. As the comparison element, 5.75 inches long withlayers outside to in of depth loading media, coalescer media, 2 layersof superabsorbent nonwoven and a double wrap of nanofiber layered on 5um Synteq XP were constructed.

Testing was run in the standard rig under the same or similar conditionsas previous testing. Each design was subjected to the saturated fuelrecirculation test and was then run through the 100 ppm water pressuredrop test. This was done to see if a difference could be noted in thewater absorbing performance and SAP migration of a filter that had beenthrough the recirculation test with and without nanofibers. The two-parttesting was conducted as follows:

In a first test a saturated fuel recirculation test was used. Using anew element and saturated fuel with no additional free water, the fuelwas circulated at 5 gpm and pressure drop was recorded for a totaltesting time of 20 min. Pressure drop, flow rate and temperature wererecorded every 5 minutes. This testing was followed by the 100 ppm teston the used elements. As a second test a 100 ppm water pressure droptest was used.

Using the element from recirculation test, saturated diesel fuel waspumped at 5 gpm and water was introduced into the pump inlet at a rateto ensure the addition of 100 ppm free water by volume into the diesel.Effluent fuel sample was collected at 1 liter sample size for filtrationthrough a 0.45 micron Millipore membrane for copper sulfate staintesting to detect super absorbent migration at the beginning and end ofthe test. Feeding of 100 ppm water and diesel to the filter wascontinued until the pressure drop reached 50 psi. During the test,pressure drop and temperature was recorded at the start andapproximately every 2 minutes. Fuel water samples were analyzed withKarl Fischer Colorimetric unit for water content.

The following procedure was followed for the laboratory analysis of SAPmigration on the effluent diesel filtered on membranes. After filteringthe effluent fuel, the contaminant remained on the gridded membrane(grid markings facilitate the subsequent SAP particle counts in astatistically random way). The membrane was then wetted with 0.5% copper(II) sulfate solution for 2 minutes. The 0.5% copper (II) sulfatesolution (w/v) was created using distilled water and copper (II) sulfatepowder (99.99%). Excess copper sulfate solution was removed by vacuumfiltration and the membrane was dried and then placed under a low poweroptical microscope and the membrane surface was examined for SAPparticles. The presence of blue particles indicating the presence of SAPwas noted and reported based on the counting of 20 grids on eachmembrane, where each counted grid was marked with a red ink pen to avoidre-counting of the same grid.

We also conducted testing for water absorbency of nanofiber. Using a newelement and saturated fuel with the one time addition of 100 ppm freewater, fuel was circulated at 5 gpm for 20 min. Pressure drop, flowrate, temperature and fuel saturation was recorded every 5 minutes. Fuelwater samples were analyzed with Karl Fischer Colorimetric unit forwater content. Two samples for each element configuration, examples 9,10 and 11 were tested. The objective of this round of testing was tofind whether hydrophilic nanofiber alone would aid in absorbing andremoval of water from diesel fuel beyond its saturation level.

Experimental Results

All fuel water testing was performed on a KF 701 volumetric tritontitrator. The two values for downstream PPM H₂O represent the waterconcentration in the test fluid using either; beginning PPM of testfluid in bench subtracted by the measured PPM at the given test time),or measured PPM at given test time subtracted by the saturated value forthe fluid. The beginning PPM for each test is reported on the very rightcolumn. Results are grouped in terms of the properties of the dieselfuel obtained from suppliers, as suppliers and the properties of thediesel fuel varied throughout the testing. Again, one point to keep inmind is that as IFT and MSEP values of the fluid increases, it becomeseasier to separate emulsified water from the fluid.

Group 1 Test Fluid Specifications Fluid Type Super America - ULS Diesel(pump untreated) Density 0.843 mN/m IFT 22.2 mN/m Surface Tension 28.1mN/m MSEP Rating 42.0 Saturated PPM 140 Test Fluid PPM H2O Diesel fuelwater Time LPM Delta P Temp PPM H2O Downstream saturation at test (min)Flow (PSI) (° C.) Downstream (Saturated) start (ppm) Baseline 0 16.08.00 23.9 0 22 162 A 2 16.0 10.00 24.9 0 0 5 15.5 13.47 25.5 0 2 10 14.324.3 26.4 0 1 16 12.9 45.39 27.5 0 9 Baseline 0 16.5 5.74 26.9 0 9 149 B2 16.0 6.35 27.4 0 0 5 16.0 7.09 27.7 0 0 17 14.0 24.6 29.6 0 6 20 12.544.90 29.5 6 15 Baseline 0 16.0 8.43 26.3 0 15 155 C 2 15.5 12.74 27.1 00 4 14.0 20.12 27.6 0 0 9 12.3 43.03 28.6 0 0 Example 0 16.5 5.3 24.9 00 127 1 2 16.5 6.88 25.1 0 0 5 16.3 9.18 25.6 0 0 14 13.0 43 26.9 14 1Example 0 17.0 2.61 27 0 0 138 2 2 17.0 2.76 27.2 0 0 5 17.0 2.98 27.5 00 15 16.8 9.79 28.4 29 27 17 12 43.16 28.8 42 40Based on the results presented above for Group 1, it is apparent thatthe coalescing media (meltblown layer) made a difference in downstreamwater concentration since Example 1 has the coalescing layer and Example2 does not have the coalescing layer. The downstream water concentrationis greater in Example 2 compared to the Example 1. With the use of acoalescer, the very fine droplets were coalesced into larger dropletsinside the fuel, which made the fuse filter more effective in terms ofcapturing and absorbing these water droplets by the superabsorbentfibrous nonwoven media.In the presence of a coalescing media superabsorbent nonwoven along withother layers that goes into the element, performed very similar to thebaseline media A, B and C. Any type of particle, fiber migrationdownstream is reduced significantly.

Group 2

As mentioned earlier, this diesel fuel was purchased from a differentlocation and hence possessed different properties most notably IFT andMSEP. In fact, the diesel used for testing of Group 2 samples was harderto work with in terms of separation and absorption of the emulsifiedwater from diesel fuel by superabsorbent fibers and particles.

Test Fluid Specifications Fluid Type Holiday - ULS Diesel (pumpuntreated) Density 0.861 mN/m IFT 19.7 mN/m Surface Tension 28.8 mN/mMSEP Rating 0.0 Saturated PPM 161 Test Fluid PPM H2O Diesel fuel waterTime LPM Delta P Temp PPM H2O Downstream saturation at test (min) Flow(PSI) (° C.) Downstream (Saturated) start (ppm) Baseline 0 16.0 7.0325.8 0 2 163 B 2 16.0 8.04 26.4 0 0 5 16.0 10.09 27.0 0 0 11 15.5 15.9227.9 46 48 15 15.0 23.47 28.6 35 37 20 13.0 43.17 29.6 48 50 Example 016.5 4.48 26.8 0 0 147 3 2 16.5 4.72 27.2 0 0 5 16.5 5.01 27.6 0 0 1116.5 7.30 28.5 30 16 13 15.0 11.50 28.8 N/A N/A 16 13.0 40.00 29.1 132113 Example 0 16.5 3.18 27.2 0 0 154 4 2 16.5 3.44 27.7 0 0 5 16.5 3.6227.9 0 0 11 16.5 5.41 28.7 N/A N/A 15 13.0 44.32 29.2 59 52 Example 0 168.5 24 0 0 142 5 2 16 9.22 24.6 0 0 5 15.5 16.72 25.3 0 0 8 12.5 41.7825.7 15 1 Example 0 16 8 25.3 0 0 152 6 2 16 9.63 25.8 0 0 5 15 21.1626.2 0 0 7 12 43 26.8 0 0The results from Group 2 reveal an improved media design as described.In terms of changes in water fuel separation as a function of fuelproperties, one can compare the results between Baseline B from Group 1and Group 2. The fuel used in Group 2 testing had a lower IFT andsignificantly lower MSEP compared to the fuel from Group 1. As a resultof such difference, Baseline B performed poorly in Group 2 testing.Examples 3 and 4 performed similarly to that of Baseline B as all threesamples allowed some amount of water penetrate downstream. Most notably,Examples 5 and 6 performed the best as they did not allow water topenetrate downstream, and the pressure drop increased at a steady rate.Looking back at the media design examples presented earlier, one cannotice that the success of Examples 5 and 6 was in large part due tocombination of superabsorbent nonwoven media working in tandem with thenanofiber super absorbent particulate or fiber composite media. Superabsorbent media was an open and thick structure that resulted in goodresidence time of the fuel inside it. During the course of the testing,it absorbed much of the water and did not close off completely due toits open, lofty fibrous nature. Any water that was not absorbed by thesuperabsorbent nonwoven media was absorbed by the nanofiber/SAP particlecomposite positioned downstream of the superabsorbent nonwoven media. Asmost of the water was absorbed by the superabsorbent nonwoven, thecomposite did not prematurely shut-close due to the water in a shortperiod of time. The quick absorption kinetics of the nanofiber/SAPparticle composite did not allow water penetrating downstream of theelement.

Group 3 Test Fluid Specifications Fluid Type Super America - ULS Diesel(pump untreated) Density 0.854 mN/m IFT 20.5 mN/m Surface Tension 28.5mN/m MSEP Rating 0.0 Saturated PPM 161 Test Fluid PPM H2O Diesel fuelwater Time LPM Delta P Temp PPM H2O Downstream saturation at test (min)Flow (PSI) (° C.) Downstream (Saturated) start (ppm) Example 0 16.3 6.7227.2 0 0 145 7 4 16.3 7.02 28.5 0 0 8 16.3 8.02 29.2 0 0 12 16.0 10.9529.7 17 6 17 12.7 42.97 30.6 34 23 Example 0 16.3 6.31 29.7 0 23 161 8 416.3 6.64 30.1 0 0 8 16.3 7.81 30.4 0 0 12 16.0 11.21 30.6 4 10 17 12.041.54 30.9 16 21The difference between examples 7 and 8 is that Example 8 has twosuperabsorbent nonwoven media face-to-face with coalescing media on oneside and 5 um Synteq XP on the other side. On the other hand, Example 7has the same two superabsorbent nonwoven media face-to-faceconfiguration with the exception that there's hydrophilic nanofibercoating on both sides, sandwiching the two superabsorbent nonwovenmedia. The nanofiber coating on downstream swell in the presence ofwater and also acts as a barrier for any possible migration of swollenstaple superabsorbent fibers, however based on the data shown forExamples 7 and 8, the water concentration downstream of the filtersappear very similar. It is our understanding that the superabsorbentnonwoven media does most of the job in terms of removing water, which isresulting in a test with poor sensitivity in regards to nanofiberfunction. Therefore, follow-up testing that proves the effectiveness ofhydrophilic nanofibers in absorbing/removing water has been carried out.

Group 4 Test Fluid Specifications Fluid Type Super America - ULS Diesel(pump untreated) Density 0.845 mN/m IFT 19.7 mN/m Surface Tension 28.1mN/m MSEP Rating    0.0 Saturated PPM 149While primary purpose of using nanofibers on a superabsorbent nonwovenis to capture any possible SAP migration, the secondary purpose of thenanofibers is to absorb any excess water. During the testing wherenanofibers were on the downstream side of the superabsorbent nonwoven,results showed no difference between the elements with and withoutnanofibers in terms of water content. In order to increase thesensitivity of the testing to the secondary function of nanofibers,superabsorbent nonwoven media was eliminated from the elementconfiguration and water absorption was carried out only by the nanofiberlayer.

Diesel fuel Test Fluid water satura- Time LPM Delta P Temp PPM H2O tionat test (min) Flow (PSI) (° C.) Downstream start (ppm) Example 0 16.35.88 23.3 139 149 9-1 5 16.3 5.87 24.6 121 10 16.3 5.87 25.9 132 15 16.55.88 26.8 134 20 16.7 5.86 27.6 132 Example 0 16.2 5.51 26.6 152 149 9-25 16.3 5.58 27.6 128 10 16.5 5.51 28.2 140 15 16.7 5.43 28.9 145 20 16.75.38 29.2 125 Example 0 16.8 5.59 27.1 161 149 10-1 5 17.0 5.77 28.1 13810 17.2 5.71 28.6 141 15 17.2 5.66 29.0 157 20 17.3 5.57 29.4 134Example 0 17.0 5.57 28.3 170 149 10-2 5 17.2 5.79 28.9 126 10 17.3 5.7529.4 135 15 17.4 5.70 29.8 122 20 17.3 5.67 30.0 153 Example 0 16.1 5.8523.6 150 149 11-1 5 16.1 5.84 23.9 99 10 16.3 5.84 24.3 122 15 16.3 5.8124.9 115 20 16.3 5.78 25.4 112 Example 0 16.0 5.86 25.4 175 149 11-2 516.2 5.86 25.7 113 10 16.2 5.84 26.4 123 15 16.3 5.82 26.6 138 20 16.25.80 26.8 139Results presented above indicate that more water was removed usingexamples 10 and 11 as compared to example 9, which did not have anynanofiber layer. The data illustrates that nanofiber can absorb waterand play as a safety role for water concentration reduction throughabsorption.

Water Slug Test—Group 1

The diesel fuel described in previous section 5.1 for Group 1 is thesame used in water slug test for Group 1 samples.

PPM H2O Test Time (sec) LPM Delta P (PSI) Downstream Baseline B 0 166.23 Not Recorded 3 <5 50+   Not Recorded Example 1 0 16.5 4.68 128 4 <550+   2231 Example 2 0 16.5 2.55 153 8 <8 50+   1276

Group 2

Here again, the diesel fuel described in section 5.1 for Group 2 is usedduring water slug tests for Group 2 samples.

PPM H2O Test Time (sec) LPM Delta P (PSI) Downstream Baseline B 0 16 6154 6 <5 65+ 7600+ Example 3 0 16 4 163 6 <5 70+ 7538  Example 4 0 16.54 156 6 <8 65+ 3149  Example 5 0 15.8 8 128 5 <7 70+  91 Example 6 015.0 7 132 5 <7 70+ 2352 

Drying of Fuel Below Saturation

One other aspect of performance that the design of the inventiondemonstrates is an ability to dry the fuel below the saturation limitfor water. Donaldson Company internal testing is based on IP DraftStandard 1583 5^(th) edition qualification test 4.5.1 Media Migrationand Starting Differential Pressure Test. The test includes adding waterto a batch of fuel until it reaches its saturation point, in this caseslightly over 150 ppm total water and then recirculating the fuelthrough the filter for 20 minutes. The data below shows total water inthe fuel decreasing from 150 ppm to 51 ppm over the 20 minuterecirculation test.

EXAMPLE 8

Saturated Recirculation results Delta P Fluid Temp PPM H2O Test Time(min) LPM Flow (PSI) (° C.) Downstream 0 16.2 4.57 25.9 150 5 16.5 4.6127.1 71 10 16.6 4.5 28.0 58 15 16.6 4.39 29.1 58 20 16.6 4.32 29.8 51

SAP Particle Migration

According to the test protocol described in the experimental section,membranes were stained and tested for migrated SAP particles using anoptical microscope. The table presented illustrates the significantdifference in terms of SAP particle counts between a filter composed ofnanofiber enhanced superabsorbent nonwoven and the version that does nothave nanofibers. It is clear that nanofibers played a key role in termsof stopping the migration of SAP particles downstream of the filter. Itis also straightforward that one can incorporate nanofibers as particleentrapping nets for not only on the downstream of the superabsorbentnonwoven but also on the upstream as well to improve the security of thefilters free of any particle migration which otherwise can take place.

Sample ID 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Total w/out6 3 6 4 7 2 4 2 7 5 3 7 14 5 3 8 6 9 6 2 109 nano fibers @ test startw/out 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 nano fibers @ test endw/ 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 nano fibers @ test start w/0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 nano fibers @ test end

The function of the structure of the invention is to work as a valve orfuse and shut off flow in the presence of free water in fuel. A criticalimprovement is demonstrated in the rapid pressure drop increase stoppingfuel loading in the event of a water contamination situation.

FIGS. 6-8 show a quicker shutoff and improved pressures for elements ofthe invention (Example 12) versus current design competitor elements ondiesel fuel with 100 ppm of free water at 5 gpm with an element ⅙^(th)the size of a standard monitor. The internal test is a modification ofQualification Test 4.5.2, 50 ppm Water Test, Full Rated Flow, from theIP Draft Standard 1583 5^(th) edition IP06/026. The testing uses dieselfuel instead of Jet A fuel and 100 ppm water. A diagram of the test rigis a FIG. 5, and the test procedure is described.

DEFINITIONS AND ABBREVIATIONS

IFT: Interfacial Tension surface tension between two immiscible liquids.Surfactancy: The amount and type of surfactant(s) in a liquid that causeapparent liquid property change such as decreased surface tension andIFT, increased conductivity, increased solubility and so on.Surface tension: It is an effect within the surface layer of a liquidthat causes that layer to behave as an elastic sheet.MSEP Rating: Microseparometer rating is an indicator of fuel surfactancyobtained by measuring the fuel turbidity after the formed water-in-fuelemulsion is filtered through a standard coalescence material.Emulsion: Emulsion is a mixture of two immiscible substances. Onesubstance (the dispersed phase) is dispersed in the other (thecontinuous phase):

ULS: Ultra Low Sulfur

Delta P: Pressure dropLPM: Liters per minutegpm: Gallons per minuteppm: parts per millionpsi: pounds per square inch

The above specification, examples and data provide a completedescription of the manufacture and use of the composition of theinvention. Since many embodiments of the invention can be made withoutdeparting from the spirit and scope of the invention, the inventionresides in the claims hereinafter appended.

1. A web comprising a substantially continuous nanofiber having adiameter of about 0.001 to 5 micron and an active particulate dispersedin the fiber layer or fiber web, the particulate comprising a superabsorbent and comprising 0.1 to 50 vol % of the web, the web having athickness of about 0.0001 to 1 cm and the super absorbent comprisesabout 0.001 to 10 kg per square meter of the layer or web.
 2. The web ofclaim 1, wherein the solidity is about 1 to 50%.
 3. The web of claim 1,wherein the web comprises a flow-by direction such that a fluid can flowin a path parallel to the web with no filtration path through the web.4. The web of claim 1, wherein the nanofiber has a diameter of about0.001 to 0.5 micron.
 5. The web of claim 1, wherein the web comprisesabout 5 to 95 wt % fiber and about 95 to 5 wt % super absorbentparticulate and the layer comprises 1 to 1000 grams of super absorbentparticulate per square meter.
 6. The web of claim 1, wherein the webcomprises about 30 to 75 wt % fiber and about 70 to 25 wt % superabsorbent particulate, the web comprising 1 to 1000 grams of superabsorbent particulate per square meter
 7. The web of claim 1, whereinthe active particulate has a major dimension less than about 5000microns.
 8. The web of claim 1, wherein the web also comprises an activeparticulate comprising an absorbent particulate, an adsorbentparticulate, a reactive particulate, or mixtures thereof.
 9. The web ofclaim 1, wherein the super absorbent particulate has a major dimensionof about 0.05 to 100 microns.
 10. The web of claim 1, wherein the webhas a Frazier permeability of about 1 to about 50 meters-minutes⁻¹ andan efficiency of about 40 to about 99.9999% under ASTM 1215-89 usingmonodispersed 0.78 micron polystyrene particulate at 6.1 m-min⁻¹ or 20ft-min⁻¹.
 11. The web of claim 1, wherein the web comprises one or morelayers of web each layer having a thickness of at least about 0.5micron.
 12. The web of claim 1, wherein the web at least a first layercomprising the super absorbent and at least a second layer comprising anactive particulate.
 13. The web of claim 1, wherein the second layercomprises an active particulate comprising a combination of an inertparticulate and an active particulate spacer means.
 14. The web of claim1, wherein the web comprises the super absorbent and an activeparticulate.
 15. The web of claim 1, wherein the web has a gradient inthe distribution of the active particulate spacer means.
 16. The web ofclaim 1, wherein the web has a gradient in the distribution of the superabsorbent.
 17. A filter media comprising a filtration substrate and theweb of claims
 1. 18. An element comprising a filter media, the mediacomprising a first and second opposite flow faces; and a plurality offlutes; (i) each of said flutes having a first open end portion adjacentto said first flow face and a second open end portion adjacent to saidsecond flow face; (ii) said media including a substrate at leastpartially covered by a web of nanofibers, said media comprising a superabsorbent particle fiber or fabric.
 19. The element of claim 18, whereina super absorbent particulate is dispersed in the nanofiber layer, theparticulate comprising 0.1 to 50 vol % of the layer, the fiber having adiameter of about 0.001 to about 5 microns, and the layer having athickness of 0.5 to 500 microns; wherein the element comprises a flow-byor flow through path such that a fluid can flow in a path parallel tothe substrate.
 20. The element of claim 18, wherein selected ones ofsaid flutes being open at said first end portion and closed at saidsecond end portion; and selected ones of said flutes being closed atsaid first end portion and open at said second end portion provides afluid path through the fluted layer.
 20. The element of claim 18,wherein the nanofiber has a diameter of about 0.001 to 0.5 micron. 21.The element of claim 18, wherein the web comprises about 5 to 95 wt %nanofiber and about 95 to 5 wt % super absorbent fiber and the nanofiberhas a diameter of about 0.001 to 0.5 micron.
 22. The element of claim18, wherein the web comprises about 30 to 75 wt % fiber and about 70 to25 wt % super absorbent particulate.
 23. The element of claim 18,wherein the super absorbent particulate has a major dimension of about0.1 to 500 microns.
 24. The element of claim 18, wherein the web has aFrazier permeability of about 1 to about 50 meters-minutes⁻¹ and anefficiency of about 40 to about 99.9999% under ASTM 1215-89 usingmonodispersed 0.78 micron polystyrene latex particulate at 6.1 m-min⁻¹or 20 ft-min⁻¹.
 25. The element of claim 18, wherein the filterstructure comprises one or more nanofiber webs having a thickness of atleast about 0.5 micron, at least one layer comprises super absorbentparticulate or fabric and at least one other layer comprises an activeparticulate.
 26. The element of claim 18, wherein the particulate activeis an absorbent.
 27. The element of claim 18, wherein the particulate isan adsorbent.
 28. The element of claim 18, wherein the particulate is areactive particulate.
 29. The element of claim 18, wherein the web has agradient in the distribution of the super absorbent particulate orfiber.
 30. The element of claim 18, wherein the web has a gradient inthe distribution of the fiber.
 31. A filter element comprising afiltration substrate and a nanofiber web comprising a substantiallycontinuous nanofiber layer, the web having a thickness of about 0.1 to100 microns and a pore size of about 0.01 to 10 microns, and a superabsorbent fabric layer or dispersed in the fine fiber, a super absorbentparticulate or fiber comprising about 0.1 to 50 vol % of the web, thesuper absorbent fiber or particulate comprising about 0.001 to 10 kg persquare meter of the membrane.
 32. The element of claim 31, wherein theelement comprises a flow-by direction such that the fluid can flow in apath parallel to the membrane with no substantial filtration paththrough the membrane.
 33. The element of claim 31, wherein the elementcomprises a flow through direction such that the fluid can flow in apath across the membrane with a substantial filtration path through themembrane.
 34. The element of claim 31, wherein the element comprisesabout 5 to 95 wt % nanofiber layer mass and about 95 to 5 wt % superabsorbent fiber or particulate and the element comprising 1 to 100 g-m⁻²of particulate.
 35. The element of claim 31, wherein the elementcomprises about 30 to 75 wt % of nanofiber layer mass and about 70 to 25wt % super absorbent fiber or particulate and the element comprising 1to 1000 g-m⁻² of particulate.
 36. The element of claim 31, wherein thesuper absorbent particulate has a major dimension of less than 500microns.
 37. The element of claim 31, wherein the super absorbentparticulate also comprises an absorbent particulate, and adsorbentparticulate, a reactive particulate or mixtures thereof.
 38. The elementof claim 31, wherein the particulate has a major dimension of about 5 to200 microns.
 39. The element of claim 31, wherein the element comprisestwo or more layers, one layer comprising the web and a second layer, thesecond layer being substantially free of particulate.
 40. The element ofclaim 31, wherein the second layer comprises a filter substrate.
 41. Amethod for treating a fluid, the method comprising: (a) directing fluidthrough a filter medium having first and second opposite flow faces; anda plurality of flutes; the medium comprising; (i) each of the fluteshaving a first end portion adjacent to the first flow face and a secondend portion adjacent to the second flow face; (ii) selected ones of theflutes being open at the first end portion and closed at the second endportion; and selected ones of the flutes being close at the first endportion and open at the second end portion; (iii) the medium including asubstrate at least partially covered by a layer of nanofibers; and (iv)a layer comprising a super absorbent particulate, fiber or fabric;wherein in the layer of superabsorbent, the superabsorbent comprises 0.1to 50 vol % of the layer, the superabsorbent comprises a particulate ora fiber having a diameter of about 0.001 to about 5 microns, the layerhaving a thickness of 0.5 to 500 microns and a solidity of about 0.1 to65%.
 42. The method of claim 43 wherein the fluid comprises a liquid.43. The method of claim 43 wherein the fluid comprises a hydrocarbonliquid.
 44. The method of claim 43 wherein the fluid comprises a liquidvegetable oil.
 45. The method of claim 43 wherein the fluid comprisesliquid hydraulic oil.
 46. The method of claim 43 wherein the liquidcomprises a fuel
 47. The method of claim 43 wherein the fluid comprisesa gas
 48. A method of removing moisture from an air stream, the methodcomprising contacting a moisture-laden air stream with a web, the webcomprising a layer comprising a substantially continuous nanofiberlayer, the nanofiber having a diameter of about 0.001 to about 5 micronsand comprising a super absorbent fabric, fiber or particulate, thesuperabsorbent comprising 0.1 to 95 vol % of the layer, the layer havinga thickness of about 0.0001 to 1 cm and the superabsorbent comprisesabout 0.001 to 10 kg-m² of the layer.
 49. The method of claim 48,wherein the web is placed in a vent for an enclosure such that theinterior of the enclosure is maintained at a substantially reducedmoisture content with respect to the exterior of the enclosure.
 50. Themethod of claim 48, wherein the enclosure comprises an enclosurecontaining an electronic circuit or device.
 51. The method of claim 48,wherein the electronic circuit or device comprises a hard drive.
 52. Amethod of removing moisture from a hydrocarbon liquid, the methodcomprising contacting a moisture containing liquid with a web, the webcomprising a layer comprising a substantially continuous nanofiberlayer, the nanofiber having a diameter of about 0.001 to about 5 micronsand comprising a super absorbent fabric, fiber or particulate, thesuperabsorbent comprising 0.1 to 50 vol % of the layer, the layer havinga thickness of about 0.0001 to 1 cm and the superabsorbent comprisesabout 0.001 to 10 kg-m⁻² of the layer.
 53. The method of claim 54wherein the hydrocarbon liquid comprises a fuel.
 54. The method of claim54 wherein the fuel comprises gasoline.
 55. The method of claim 54wherein the fuel comprise diesel fuel.
 56. The method of claim 54wherein the hydrocarbon liquid comprises ethanol.
 57. The method ofclaim 54 wherein the fuel comprises jet aviation fuel.
 58. The method ofclaim 54 wherein the liquid comprises a lubricant.
 59. The method ofclaim 54 wherein the lubricant comprises a grease.
 60. The method ofclaim 54 wherein the lubricant comprises an oil.
 61. The method of claim54 wherein the lubricant comprises a cutting oil.
 62. A method ofremoving moisture from an air stream transiting a vent in a disc drive,the method comprising contacting a moisture-laden air stream with a web,the web in the disc drive vent, the web comprising a layer comprising asubstantially continuous nanofiber layer, the fiber having a diameter ofabout 0.001 to about 5 microns and comprising a super absorbent fiber orparticulate in the nanofiber layer, the particulate comprising 0.1 to 50vol % of the layer, the layer having a thickness of about 0.0001 to 1 cmand the active particulate comprises about 0.001 to 10 kg-m⁻² of thelayer.
 63. The method of claim 64, wherein the web is placed in a ventfor an drive enclosure such that the interior of the enclosure ismaintained at a substantially reduced moisture content with respect tothe exterior of the enclosure.
 64. A web comprising a layered compositecomprising: (a) a substantially continuous nanofiber layer, thenanofiber having a fiber diameter of about 0.01 to 5 micron; and (b) asuperabsorbent fabric wherein the fabric comprises a layer having athickness of greater than 100 microns.
 65. The web of claim 64 whereinnanofiber is formed on a scrim.
 66. The web of claim 64 wherein the webcomprises a filter layer.
 67. The web of claim 66 wherein the filterlayer can accumulate particulate having a particle size of about 1 to100 microns.
 68. The web of claim 64 wherein the layered compositecomprises, in order: (a) a substantially continuous nanofiber layer, thenanofiber having a fiber diameter of about 0.01 to 5 micron; (b) asuperabsorbent fabric wherein the fabric comprises a layer having athickness of greater than 100 microns; and (c) a substantiallycontinuous nanofiber layer, the nanofiber having a fiber diameter ofabout 0.01 to 5 micron.
 69. The web of claim 64 wherein the layeredcomposite comprises, in order: (a) a filter layer; (b) a substantiallycontinuous nanofiber layer, the nanofiber having a fiber diameter ofabout 0.01 to 5 micron; (c) a superabsorbent fabric wherein the fabriccomprises a layer having a thickness of greater than 100 microns; (d) asubstantially continuous nanofiber layer, the nanofiber having a fiberdiameter of about 0.01 to 5 micron; and (e) a filter layer;
 70. The webof claim 69 wherein the filter layer comprises a bicomponent layerhaving a basis weight of about 10 to 100 g-m⁻² and a thickness of about2 to 50 microns.
 71. The web of claim 69 wherein the nanofiber layercomprises an efficiency of greater than about 95% with a 0.3 micron testparticle at 10.5 ft-min⁻¹.
 72. The web of claim 64 wherein thesuperabsorbent fabric comprises a layer comprising a basis weight ofabout 50 to 500 g-m⁻² and a thickness of about 0.2 to 40 mm.
 73. Afilter element comprising a core and at least one layer of the media ofclaim
 64. 74. The element of claim 73 wherein the core comprises aperforate core or a screen support.
 75. A hydrocarbon fuel fuse capableof stopping fuel flow in the presence of water contamination, the fusecomprising the element of claim
 73. 76. A method of stopping fuel flowin the presence of water contamination, the method comprises: (a)flowing fuel containing at least 10 ppm water, based on the fuel, in astream from a source through a conduit into a fuel tank, the stream alsopassing through a fuse comprising the web of claim 64, and (b) removingthe conduit from the tank at such a time that the contaminated fuel flowis stopped by the action of the fuse.
 77. A method of removing dissolvedor dispersed water from a fuel, the method comprising: (a) flowing fuelcontaining at least 10 ppm water, based on the fuel, in a stream from asource through a conduit into a fuel tank, the stream also passingthrough a filter element comprising the web of claim
 64. 78. The fuelfuse of claim 75 wherein the fuse is capable of stopping fuel flow whenthe differential pressure across the fuse is from 1-50 psi.
 79. The fuelfuse of claim 78 wherein the fuse is capable of stopping fuel flowwithout superabsorbent material migrating out of the fuse.
 80. Themethod of claim 48 wherein the web absorbs water droplets andcondensation from the moisture-laden air entering a gas turbine inlet.81. The method of claim 48 wherein the web is placed in a vent for anenclosure or housing to absorb water droplets and condensation frommoisture-laden air exiting the enclosure or housing.